Currently, there is a tendency for planning the maintenance and repair of the equipment (MRO) based on its actual technical condition. The current technical condition of electrical equipment is ...usually assessed using an integrated parameter called Technical Condition Index (TCI). Comprehensive evaluation of the technical condition of electrical equipment without taking it out of service is enabled by a combination of several factors, such as providing electrical equipment with automated multipurpose diagnostic and monitoring systems along with sensors for monitoring specific parameters, and developing algorithms for processing large amounts of data using, in particular, artificial intelligence methods. The TCI forecasting is used to ensure optimized planning of the electrical equipment MRO. In accordance with the applicable regulatory standards, forecasting of the changes in the technical condition of the electrical equipment is currently performed in a simplified manner using a linear function. In order to forecast the TCI of a transformer, the authors propose to use more complex mathematical methods, including machine-learning techniques. The models used to forecast the technical condition index of a power transformer, currently under development, will improve the efficiency of maintenance and repair planning based on the current and forecasted states of the electrical equipment of the electrical network. The paper presents the results of the development and testing of algorithms for forecasting transformer TCI by considering as an example a double-wound step-down transformer with a 220 kV high-voltage winding. The TCI forecasting algorithms were tested using historical datasets, containing a different number of parameters reflecting the change in the technical condition of the transformer during operation.
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•Benzoxazole substituted spirobipyrans have been synthesized.•Spirobipyrans exhibit dual positive photochromism.•Benzoxazole substituted spirobipyrans possess ionochromic properties.
...Novel photochromic spirobipyrans bearing benzoxazole group in the 3H-naphthopyran fragment have been synthesized. Spiro-conjugated benzopyran and naphthopyran fragments cause the observed dual photochromism of the molecules. In the presence of Cd2+, Mn2+, Co2+, Ni2+, Zn2+, Cu2+ metal ions thermal isomerization of the spirobipyrans is observed, followed by the formation of the intensely coloured complexes of the merocyanine form. The long-wavelength absorption band of the complexes is located at λ>600 nm.
The results of a study of the influence of the crystal structure features of organic linear conjugated oligomers on the trends of their crystallization from solutions are given.
It is shown that the substitution of 5% ferroactive molybdenum cations for iron to the La
0.6
Sr
0.4
Co
0.2
Fe
0.8
O
3 – δ
(LSCF) structure leads to a considerable increase in the electric ...conductivity. Using the powder X-ray diffraction technique, the solubility limit of molybdenum in the structure of rhombohedral perovskite is found. It is noted that the transport characteristics of perovskite with the La
0.6
Sr
0.4
Co
0.2
Fe
0.75
Mo
0.05
O
3 – δ
(LSCFM5) composition are sufficient for using it as the cathode material in intermediate temperature solid oxide fuel cells (IT SOFCs).
Currently, low-capacity power plants, connected to distribution networks of medium voltage class near electricity consumers, are increasingly being used. At the same time, the integration of ...distributed generation (DG) objects into distribution networks leads to the emergence of a set of issues associated with the implementation of relay protection: power flows through power lines in both directions; the ratio of operating currents and short-circuit currents significantly depends on the operating mode of generating stations included in the distribution network; multipoint feeding of the short circuit point can occur; modes untypical for distribution networks can occur, including swinging and asynchronous run. It should be noted that distribution networks, as a rule, in most cases are equipped with simple overcurrent non-directional protections. The conventional approach to calculating relay protection setpoints loses its effectiveness, as a result of which the sensitivity and selectivity of protection decreases, and situations arise when it is impossible to select universal setpoints for all modes of operation. Thus, it is necessary to develop adaptive relay protection systems that would take into account all possible variations in the operation modes of the distribution network, generating stations, and consumers and would adjust the parameters of the operation of their functional components. In the practical implementation and use of systems that automatically calculate and adjust the setpoints of relay protection and automation, there are a number of tasks that require compulsory study: the setpoints of the same protections from different manufacturers may differ in semantics and, in some cases, qualitatively and quantitatively (especially important for differential protections); in addition to calculation, coordination of variations in setpoints in protection devices located at different objects is required; to reduce the time for calculating modes and setpoints, it is required to limit the area of the considered network by generating equivalents for the external electrical network with updating their parameters online. By using the generated model of the electrical network, the modes are calculated. The results of the calculation of the modes are subsequently used to calculate the parameters of the protection operation and verify the sensitivity. Following that, the operation parameters grouped by modes are adaptively adjusted in the RPA devices.
Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percent in Au+Au collisions at √SNN = 200 GeV, with no significant difference between Λ and Λ¯. These new ...results reveal the collision energy dependence of the global polarization together with the results previously observed √SNN = 7.7 – 62.4 GeV and indicate noticeable vorticity of the medium created in non-central heavy-ion collisions at the highest RHIC collision energy.
The Λ (Λ¯) hyperon polarization along the beam direction has been measured in Au+Au collisions at sNN=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the ...hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (pT) dependence at pT greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown–Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.
The structural evolution of three electrocatalytic systems for hydrogen evolution reaction using iron, cobalt, and ruthenium(II) clathrochelate complexes as catalysts in a water electrolyzer is ...studied by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) spectroscopy. The complexes are shown to display essentially different robustness under water electrolysis conditions in pilot-scale hydrogen generators. The iron and cobalt(II) clathrochelates preserve their cage, macrobicyclic structure, and the encapsulated metal(II) ion is reduced to metal(I) cation; whereas in the case of ruthenium(II) clathrochelate, the cage complex undergoes partial decomposition to form sulfur-containing products of decomposition of the encapsulating macrobicyclic hexasulfide ligand, which results in the accumulation of the ruthenium disulfide RuS
2
in used clathrochelate-containing cathode material. Taking into account our experimental data on the chemical transformation of clathrochelate electrocatalysts under the conditions of 2Н
+
/Н
2
reaction, we discuss the possibilities for boosting the efficiency of electrocatalytic systems based on this class of coordination compounds.
Agriculture needs new types of drugs to combat harmful microorganisms, the introduction of which will reduce the ingress of unnecessary chemical compounds into products. It is necessary to use ...anolytes more widely as alternative means of disinfection. The use of anolytes in various fields of industries has proven their high effectiveness and harmlessness. However, the production of anolyte is a complex electrochemical process, which results in a mixture of the necessary metastable elements. To obtain an anolyte with the required set of properties, it is necessary to study the physical and chemical processes of the activator in detail. The article proposes to use Comsol software for these studies. As a result of the modeling, the characteristics of changes in the concentrations of individual chemical elements over time and the main physical dependences of the activator itself were obtained. The analysis of changes in concentrations of chemical compounds confirmed the adequacy of mathematical models. There were installed points on electrodes with significant density of currents. Studies of changes in the hydrogen index and temperature allow you to set the required operating time of the activator. Analysis of concentrations of chlorine-containing compounds proves the difficulty of determining the rates of formation of individual chemical formations and their instability. On the basis of the obtained data, it is possible to recommend the mode of operation of the electrical activator depending on the properties of the source water and the requirements to the resulting solution.
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