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Number of results: 8
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Abstract

The paper presents an analysis of overvoltages caused by a direct lightning strike in intrusion detection system equipped with underground radiating cable sensors. Waveforms of currents and voltages in the system components are calculated using analytical formulas basing on a transmission-line model in the frequency domain. The time-domain waveforms are computed using the inverse fast Fourier transform (IFFT). Three network configurations of the intrusion detection system are analyzed.

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Authors and Affiliations

K. Aniserowicz
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Abstract

Modern electrical-power systems are often exploited for transmitting highfrequency carrier signals for communications purposes. Series-connected air-core coils represent the fundamental component allowing such applications by providing a proper filtering in the frequency domain. They must be designed, however, to withstand also the line short-circuit current. When a high-magnitude current flows through a coil, strong mechanical stresses are produced within the conductor, leading to possible damage of the coil. In this paper, an approximate analytical model is derived for the relationship between the maximum mechanical stress and the electrical/geometrical parameters of the coil. Such a model provides the guidelines for a fast and safe coil design, whereas numerical simulations are only needed for the design refinement. The presented approach can be extended to other applications such as, for example, the mechanical stress resulting from the inrush currents in the coils of power transformers.
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Authors and Affiliations

D. Bellan
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Abstract

This article proposes an analytical model of a system with priorities servicing a mixture of different elastic traffic streams. The model presented in the article was developed as the extension of earlier works published by the authors. It utilizes the concept of equivalent bandwidth and then, following bandwidth discretization, uses the dependencies introduced on the basis of the assumptions adopted for the generalized Kaufman-Roberts formula and for the model of a full-availability group with traffic compression. The article presents a possibility of using the proposed model to model the radio interface in a multi-service mobile network and provides an example of the above with the interface of an LTE network. Since the proposed model is an approximate one, the results of the calculations are compared with the results of simulations. A comparison of the results confirms an acceptable level of accuracy of the model. The model can be successfully used in the analysis and design of links and nodes of telecommunication and computer networks.

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Authors and Affiliations

B. Nowak
ORCID: ORCID
M. Piechowiak
M. Stasiak
P. Zwierzykowski
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Abstract

A new expression is proposed to calculate the earth-energy of an earth-air-pipe heat exchanger during winter heating for three kinds of soil in France. An analytical model is obtained by using numerical computation developed in Scilab – a free open source software. The authors showed the comparison between their simple analytical model and experimental results. They showed the influence of different parameters to specify the size of the heat exchanger.

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Authors and Affiliations

Vincent M.F. Molcrette
Vincent A.R. Autier
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Abstract

The paper presents analytical relationships based on the theory of Green’s functions. The relationships refer to instantaneous and continuous as well as point and ring heat sources which are discussed. The relationship relating to continuous ring source is the basis for modelling and designing of spiral ground heat exchangers. Heat transfer in the infinite and semi-infinite body was considered. In the latter case, the image method was discussed. Using the results of measurements regarding heat transfer in the ground with a heat exchanger in the form of a single coil installed, a comparison of calculated ground temperatures with measured values was presented.

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Authors and Affiliations

Barbara Larwa
Krzysztof Kupiec
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Abstract

Vertical transport of wall-panels is a part of the prefabrication process of wood-framed buildings. The total dead weight of a wall is suspended on several lifting slings, pointwise clasping the top plate of the wall. This indicates, that all the weight of a wall is cumulated in sheathing-to-framing fasteners, usually staples. This article presents experimental investigations and analytical models evaluated for the description of light wood-framed walls in the process of lifting. Three different models cover the analytical approach: a model of a simple beam on elastic supports (BSS), a model of assembled beams (ACBS), three-dimensional (3D) spatial FE model of the wall (WFEM). Board-to-beam joint material parameters are determined on the base of experimental results. These connections are converted into two variants in the form of spring elements for 2D analysis, and beam elements for 3D analysis.
The numerical results exhibit that the proposed models may correctly represent behavior of a real wall in lifting, applying elastic materials parameters.
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Authors and Affiliations

Jarosław Malesza
1
Czesław Miedziałowski
1
ORCID: ORCID

  1. Bialystok University of Technology, Faculty of Civil Engineering and Environmental Sciences, Wiejska 45A, 15-351 Bialystok, Poland
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Abstract

Divorced eutectoid growth of cementite in AISI 1080 steel is investigated as a function of cooling rate for incomplete austenitization-based heat treatment. Furthermore, a fundamental mathematical relationship is established through analytical treatment that correlates divorced eutectoid growth with effective cooling rate and degree of undercooling in view of bulk diffusion controlled growth model. As the cooling rate increases, the divorced eutectoid growth of cementite is gradually ceased. The result predicted by the analytical model closely matches with the experimental result (%Deviation ≤ 7).

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Authors and Affiliations

Prasenjit Biswas
Joydeep Maity
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Abstract

Dynamic characteristics for three types of railgun constructions were simulated and measured in this work. The simplest construction is the iron-less (IL) railgun, while the two other ones (IC and ICPM) have an iron-core. The iron-core permanent magnet (ICPM) railgun additionally has permanent magnets. To compare their characteristics, similar dimensions of the rails and iron cores were adopted, and the same power supply system was used. Numerical magnetic field analyses and our analytical models have been used to determine the electromagnetic parameters. They were verified experimentally. The transient states of the railguns were studied with our field-circuit mathematical model, and their results were also verified by experiments.
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Authors and Affiliations

Paweł Piekielny
1
ORCID: ORCID
Bronisław Tomczuk
1
ORCID: ORCID
Andrzej Waindok
1
ORCID: ORCID

  1. Department of Electrical Engineering and Mechatronics, Opole University of Technology, Prószkowska 76 str., 45-758 Opole, Poland

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