• Energy Research
• Open Access close
• Closed Access close
• Restricted close
• US close
• CA close
• CN close
• Russian close

The errors between the design parameters and experiment data of the power transformer in idle mode can reach 15-20% or more, because engineering techniques do not take into account in full all factors. Therefore, the aim of the work is to develop improved circuit models, which are interconnected with spatial electromagnetic field models. These models consider the active part design of the transformer, the hysteresis of the nonlinear magnetic properties of electrical steel, asymmetry and non-sinusoidal phase-to-phase currents and provide high accuracy determination of rated idling parameters of transformer. To research the idle mode of transformer, the circuit models were conjugated with 3D and 2D magnetic field models. Their numerical implementation was carried out by means of finite element method on the example of a three-phase power transformer (10 kVA, 380/220 V). The reduction of the computational time was performed by doubling cancellation of the volume of 3D three-phase transformer domain and the conformal transition to the 2D geometric domain. Determination of the effective magnetic characteristics of electrical steel according to single-phase idling experiment data, allows to take into account the combined effect of hysteresis and eddy currents, design and technological factors on the specific losses and magnetization power. This ensures high accuracy of the description of the interrelation between magnetic flux density and magnetic field strength, reducing of current error and relative errors in the calculation of idling losses up to 1.41% and 1.2% for the 3D model and up to 5.18% and 3.2% for the 2D model.

Today, the significant volumes of network traffic circulate through the Internet. The sources of such traffic are, in particular, the diverse territory distributed “smart” devices. The number of named devices is about billions. As a consequence, the relevance of bringing to practice the core concepts of the Internet of Things paradigm is constantly becoming more and more topical. It’s bound with the problem of granting the interoperability between the components of distributed software systems, built over the aforementioned devices. The web services are typically considered as the components of the system. To this end, to establish the interoperability between the components, despite the standardization, the need for the development of effective tools and techniques, granting the interoperability between the web services, arises. The goal of the work is to increase the effectiveness of the Internet of Things system engineering process by way of checking the interoperability between the components during the designing. The goal is achieved through the development of formal model for checking the interoperability between the components of the Internet of Things system by way of model checking in an automated manner. The novelty of proposed solution is grounded on the usage of Temporal Logic of Actions, corresponding formalism and the concept of action as the basis for compact and easily reconfigurable formal specifications synthesis. The adequacy of proposed model has been proved through the case study. The verification-related time costs have been estimated.

Four folded maps tipped in. ; Mode of access: Internet.

The presence of higher current harmonics has a negative impact on the efficiency and reliability of the elements of network. Higher current harmonics can lead to significant increases of resistance, voltage drop and active losses in busbar, also to decreasing network power factor. Existing engineering techniques can’t provide a reliable calculation of the parameters of busbars at higher current harmonics influences. Therefore, the aim of the work is to develop a new approach of parameters determination and the voltage drop estimation in busbar at higher current harmonics influence. Mathematical model of electromagnetic processes in busbar, which takes into account their design features, non-linearity of magnetic and electrophysical properties, proximity effects, surface and external surface effects, was developed and proposed. This model will allow to determinate the components of active and reactive resistances of busbar, voltage drops for each eigenvalue of the amplitude and frequency of current harmonics. Based on field simulation results was obtained the functional dependence in bicubic polynomial form. For effective spectra and amplitudes of higher harmonics, at selecting the corresponding polynomial coefficients, it will allow to determinate the components and the resulting values of voltage drops for an individual busbar’s design without spending time on field simulation. Based on the proposed approach, a method will be developed for the busbar's parameters identification and voltage drop estimation. This will allow effectively define the network configuration, installed capacity of compensating devices, which will provide the reliability of electrical collectors with the declared technical data and etc.

The article proposes a method for reducing time necessary for subsuming a certain document in order to classify the text documents by reducing the term vector size of certain categories. According to the method, the term weight factors were calculated for each classification category to implement subsuming process at the stage of training a certain system. As a result of the analysis of the obtained data, the individual category terms, whose weight values did not exceed the experimentally determined threshold value, were excluded from the term vector of the category by equating them to zero. Those terms were not involved in the further subsuming process at the testing stage. As the input data for the experimental part, the TF-SLF reference method and its modernization CTFSLF according to those described above were proposed. Due to the application of the method proposed, the differential term vector size for each category was decreased. Despite the increase in the compile time of the term vector according to categories, which was performed only once, the calculation time used to determine whether or not a document belonged to a specific category decreased without losing the classification quality. In addition, due to the fact that the proposed method excluded the words that were used in the texts frequently, it became possible to exclude the stage of removing the stop words from the pretreatment process of the analyzed text. For the same reason, the problem of misprints and the words "stuck together" in the initial, training sample was solved

Scientific, educational, cultural and educational network journal "Journal of Environmental Earth and Еnergy Study (JEEES)", No 3/2020. 

The article examines potential integration of government initiatives in the field of environmental protection and policies aimed at the development of energy sector of the Russian Federation. The analysis, carried out on the basis of national ecological projects and the energy strategy of the Russian Federation, reveals that the two planning areas are practically disjoint. This indicates that integrated approach towards solving the issue of global warming through modification of energy supply and demand patterns, which is dominant in many Western countries, has little political support in Russia. The article concludes that the goal to combat climate change, pronounced by the Russian government, has not been followed through in the factual government plans.

Digital Image Processing to assess Ice coasts changes in the Russian Arctic, Spitsbergen. Student Internship at Joanneum Research, Graz, Austria.