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1

Two-dimensional modeling positive and negative streamer discharge at high pressure

Boukreris A., Mekri A., Kraloua B., Hennad A.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 6

27--32

EN

The propagation of negative and positive streamer in electric discharge can be described by solving of a two-fluid model for charged particles. It based of continuity equations for the positive ions and electrons (also called drift-diffusion equations) including the effects of ionization, electron diffusion, and photoionization coupled to the Poisson’s equation. The validity of this model is demonstrated and presented by performing of ADBQUICKEST method in two-dimension form. This new method is employed for the solution of transport equations of charged particles by using the time splitting method. The results so obtained by numerical simulations for streamer discharge are analyzed and compared with previously published experimental data.

PL

Propagacja ujemnego i dodatniego przepływu w wyładowaniu elektrycznym może być opisana za pomocą modelu dwupłynowego. Opiera się ona na ciągłych równaniach dodatnich jonów i elektronów (zwanych także równaniami dyfuzji dryfu), w tym efektów jonizacji, dyfuzji elektronów i fotojonizacji sprzężonej z równaniem Poissona. Ważność tego modelu przedstawiono w metodzie ADBQUICKEST w postaci dwuwymiarowej. Metodę tę stosuje się do rozwiązania transportu cząstek za pomocą metody podziału czasu. Wyniki uzyskuje się za pomocą symulacji numerycznych dla wyładowania streamera.

2

Integrals of a One-Dimensional Continuity Equation Along the Trajectories of Liquid Planes

Dowkontt S., Dowkontt G.

Machine Dynamics Research

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2018

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Vol. 42, No. 4

17--31

EN

Authors presents the integration of a one-dimensional continuity equation of a new flow model, along the trajectories of liquid planes. That was made possible by expressing the fluid velocity u with partial derivatives of the function ζ - a function which expresses the position of liquid planes in the flow relative to the positions they occupied when the fluid was at rest. Consequently, the one-dimensional continuity equation has become integrable. This work was signaled in previous authors articles with a description of the process of obtaining formulas, that showing partial derivatives of the function ζ - by integrating a one-dimensional continuum equation along the fluid plane trajectory. In addition, this work is a complement of the previous works, in which the integral of the one-dimensional continuity equation along the straight lines x = const and t = const in the rectangular coordinate system x,t were derived. This work also includes the integral of the differential equation of liquid plane trajectories expressing the function η, which keeps a constant value along these trajectories. In addition, the content of the work consists a necessary explanations and, on the end, additional proof of the derived equations.

3

Integrals of the one-dimensional continuity equation

Dowkontt S., Dowkontt G.

TTS Technika Transportu Szynowego

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2016

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R. 23, nr 12

77--81

EN

The authors analyze the method used by Cauchy and Lagrange to obtain the integral of continuity equation. The authors propose their own method of integration using Schwarz’ theorem. As a result, the authors obtain a greater number of possible solutions with a higher level of generality while also being able to identify the basic disadvantages of the Cauchy-Lagrangian method. Further, the authors conducted a detailed interpretation of the results of their solution.

4

Równania hydrodynamicznego smarowania poprzecznych łożysk ślizgowych z uwzględnieniem starzenia się oleju

Sikora G., Miszczak A.

Logistyka

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2015

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nr 4

5649--5656, CD2

PL

Celem niniejszej pracy jest przedstawienie równań podstawowych hydrodynamicznej teorii smarowania w których uwzględniona będzie zmiana lepkości oleju smarującego od ciśnienia, temperatury, prędkości ścinania i czasu eksploatacji. Do analizy hydrodynamicznego smarowania przyjęto laminarny przepływ cieczy smarującej oraz nieizotermiczny model smarowania łożyska ślizgowego. Przyjęto walcowe łożysko ślizgowe o skończonej długości z gładką panewką o pełnym kącie opasania. W pracy przedstawiono równania podstawowe: równanie pędu, równanie ciągłości strugi, równanie zachowania energii we współrzędnych walcowych. Do rozważań przyjęto czynnik smarujący o nienewtonowskich właściwościach. Zmiany lepkości z czasem eksploatacji zamodelowano funkcją wykładniczą na podstawie wyników badań eksperymentalnych. Zaproponowano również przyjęcie modelu Corssa zmian lepkości dynamicznej w funkcji szybkości ścinania.

EN

The purpose of this paper is to present the basic equations of the hydrodynamic lubrication theory. Change of the oil viscosity in this equations depends on pressure, temperature, shear rate and exploitation time. Assumptions for the hydrodynamic lubrication analysis are laminar flow of the lubrication fluid and nonisothermal lubrication model. Considerations apply cylindrical journal bearing of finite length with a smooth bushing and full wrap angle. This paper presents the basic equations: momentum conservation equation, continuity equation, conservation of energy equation in cylindrical coordinates system. For the consideration, the non-Newtonian lubrication fluid was assumed. Dependence of the dynamic viscosity on the exploitation time was modeled by the exponential function based on the results of experimental studies. There was also cross model proposed to describe changes in dynamic viscosity in the changes of shear rate.

5

Implementation of a quantized line element in Klein-Gordon and Dirac fields

Bulathsinghala D. L., Wijewardena Gamalath K. A. I. L

International Letters of Chemistry, Physics and Astronomy

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2015

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Vol. 48

68--86

EN

In this paper an ansatz that the anti-commutation rules hold only as integrated average over time intervals and not at every instant giving rise to a time-discrete form of Klein-Gordon equation is examined. This coarse-grained validation of the anti-commutation rules enables us to show that the relativistic energy-momentum relation holds only over discrete time intervals, fitting well with the timeenergy uncertainty relation. When this time-discrete scheme is applied to four vector notations in relativity, the line-element can be quantized and thereby how the physical attributes associated with time, space and matter can be quantized is sketched. This potentially enables us to discuss the Zeno’s arrow paradox within the classical limit. As the solutions of the Dirac equation can be used to construct solutions to the Klein-Gordon equation, this temporal quantization rule is applied to the Dirac equation and the solutions associated with the Dirac equation under such conditions are interpreted. Finally, the general relativistic effects are introduced to a line-element associated with a particle in relativistic motion and a time quantized line-element associated with gravity is obtained.

6

Corona current concept in lightning return-stroke models of engineering type

Masłowski G.

Archives of Electrical Engineering

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2010

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Vol. 59, nr 3-4

177-188

EN

A role of radial corona current in a lightning discharge is discussed in the paper. It is shown that the corona current concept previously introduced by Cooray for lightning return stroke models of distributed-current-source (DCS) type, and later, by Maslowski and Rakov for lumped-current-source (LCS) type models enables to show duality between these two types of models. Further, it is demonstrated that the corona current is useful during consideration of dynamics of the lightning-channel corona sheath. As an example of application of presented approach a relaxation model of charge motion in the corona sheath is analysed together with plots which show the rate of expansion and shrinkage of the lightning corona sheath on both microsecond and millisecond time scales.