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1

Progression of clock DBD changes over time

Maciuk Kamil, Varna Inese, Kudrys Jacek

Metrology and Measurement Systems

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2023

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Vol. 30, nr 3

499--505

EN

Day-boundary discontinuity (DBD) is an effect present in precise GNSS satellite orbit and clock products originating from the method used for orbit and clock determination. The non-Gaussian measurement noise and data processing in 24 h batches are responsible for DBDs. In the case of the clock product, DBD is a time jump in the boundary epochs of two adjacent batches of processed data and its magnitude might reach a couple of ns. This article presents the four GNSS (Global Navigation Satellite System) systems DBD analysis in terms of change over an 8 year period. For each of 118 satellites available in this period, the yearly value of DBD was subject to analysis including standard deviation and frequency of outliers. Results show that the smallest DBDs appear in the GPS system, the biggest - for the BeiDou space segment. Moreover, the phenomenon of changes in DBDs over time is clearly seen at the beginning of the analysed period when the magnitude and number of the DBDs were larger than for current, newest clock products.

2

Application of Plasma Actuator with Two Mesh Electrodes to Active Control of Boundary Layer at 50 Hz Power Supply

Gnapowski Ernest, Pytka Jarosław, Gnapowski Sebastian, Józwik Jerzy, Tomiło Paweł

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 1

58--63

EN

Numerous studies are conducted to improve the flow in the boundary layer to ensure laminar flow and in particular to increase flight safety. A new solution used to improve the laminar flow is the plasma actuator. The classic configuration of DBD plasma actuators is commonly used with the asymmetric electrode system. The manuscript describes the results of tests with a plasma actuator. Experimental tests were carried out on the built model of the wing with the SD 7003 profile, a plasma actuator was mounted on the upper surface. In contrast to the commonly used solution with solid tape copper electrodes, the novelty in the described research in the manuscript is the use of a large GND electrode (covering 70% of the upper surface of the wing) and a HV mesh electrode. The use of a plasma actuator on the upper surface of the wing affects the air flow in the boundary layer as a result of air ionization. The tests were carried out for a supply voltage from V = 7.0 kV to 12 kV and Reynolds number, Re = 87500 to 240000, flow velocity during the tests in the tunnel was in the range of U = 5-15 m/s and the angle of attack α = 5 -15 degrees. On the basis of the results experimental tests, the percentage change in the lift coefficient was calculated for the switched on and off DBD system. The obtained results indicate a maximum 17% increase in the lift coefficient for the plasma actuator activated for air flow U = 5 m/s and angle of attack α = 5 degrees. In the remaining configurations, changes in the lift coefficient amounted to 4%.

3

A mixed type boundary-value problem related to the electrostatics of cold plasma jet reactors based on dielectric barrier discharge

Vafeas Panayiotis, Papadopoulos Polycarpos K., Svarnas Panagiotis

International Journal of Applied Mathematics and Computer Science

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2021

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Vol. 31, no. 2

233--245

EN

A semi-analytical model is presented for the determination of the electric field in reactors used for cold atmospheric pressure plasma (CAPP) jet production, based on the concept of dielectric barrier discharge (DBD). These systems are associated with various applications in contemporary engineering, ranging from material processing to biomedicine, and at the same time they provide many challenges for fundamental research. Here, we consider a simplified system configuration of a single driven electrode, surrounding a thin dielectric tube, which does not contribute to the electric field, since the potential variation is immediate due to its negligible size. By employing the cylindrical coordinate system that perfectly fits the present plasma jet reactor, we separate the area of electric activity into three distinct domains according to the imposed external conditions, while our analysis is restricted to the electrostatic limit of Maxwell’s equations. To this end, cylindrical harmonic field expansions are used for the potential, which produce the corresponding electric fields in each subdomain. Due to the imposed mixed-type boundary value problem, additional linear terms are incorporated, leading to three possible analytical solutions of the physical problem under consideration. The efficiency of the method is demonstrated by comparing the final formulae with a numerical solution, followed by the relevant discussion.

4

Hydrophilization of Polyester Textiles by Nonthermal Plasma

Azeem Musaddaq, Javed Asif, Morikawa Hideaki, Noman Muhammad Tayyab, Khan Muhammad Qamar, Shahid Muhammad, Wiener Jakub

Autex Research Journal

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2021

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Vol. 21, no. 2

142--149

EN

Polyester is a popular class of material used in material engineering. With its 0.4% moisture regain, polyethylene terephthalate (PET) is classified as highly hydrophobic, which originates from its lack of polar groups on its backbone. This study used a parallel-plate nonthermal plasma dielectric barrier discharge system operating at medium pressure in dry air and nitrogen (N2) to alter the surface properties of PET fabrics to increase their hydrophilic capabilities. Water contact angle, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were utilized to analyze any effect from the plasma treatment. The wettability analysis revealed a reduction in the contact angle of more than 80% within 5 min for both discharges. Scanning electron microscopy analysis showed no microscopic damage to the fiber structure, guaranteeing that the fabrics’ structural integrity was preserved after treatment. AFM analysis showed an increase in the nanometer roughness, which was considered beneficial because it increased the total surface area, further increasing the hydrophilic capacity. XPS analysis revealed a sharp increase in the presence of polar functional groups, indicating that the induced surface changes are mostly chemical in nature. Comparing that of untreated fabrics to treated fabrics, a Increase in water absorption capacity was observed for air-treated and N2-treated fabrics, when these fabrics were used immediately after plasma exposure.

5

Modeling glow discharge at atmospheric pressure in argon

Zach T. N., Kraloua B., Hennad A.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 7

191--194

EN

This paper presents the characteristics of radio frequency atmospheric pressure discharge in argon based on numerical modeling. A fluid model with one-dimensional based on the first three moments of Boltzmann equation, coupled with Poisson’s equations used in this work. The discharge usually consists of several locally filaments. The Radio-Frequency generator with an appropriate width and period, it was found possible to control the filament to glow transition in order to obtain diffused and stable plasma. The model allows us to obtain the axial distributions parameters of the discharge at different times of Radio-Frequency cycle (RF). The principal parameters are the electronic density, ionic density, electric potential, electric field and electronic temperature.

PL

W artykule przedstawiono charakterystykę wyładowań atmosferycznych o częstotliwościach radiowych w argonie na podstawie modelowania numerycznego. Model płynny z jednowymiarowym na podstawie pierwszych trzech momentów równania Boltzmanna, w połączeniu z równaniami Poissona użytymi w tej pracy. Wyładowanie zwykle składa się z kilku lokalnych włókien. Stosując generator częstotliwości radiowej o odpowiedniej szerokości i okresie, okazało się możliwe kontrolowanie żarzenia do przejścia poświatowego w celu uzyskania rozproszonej i stabilnej plazmy. Model pozwala nam uzyskać parametry rozkładu osiowego wyładowania w różnych okresach cyklu częstotliwości radiowych (RF).

6

Multi-DBD plasma actuator for flow separation control around NACA 0012 and NACA 0015 airfoil models

Berendt A., Podliński J., Mizeraczyk J.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 8

18-21

EN

In this paper application of innovative multi-DBD plasma actuator for flow separation control is presented. The influence of the airflow generated by this actuator on the flow around NACA 0012 and NACA 0015 airfoil models was investigated. The results obtained from 2D PIV measurements showed that the multi-DBD actuator with floating interelectrode can be attractive for leading and trailing edge separation control.

PL

W niniejszej pracy zaprezentowano innowacyjny aktuator plazmowy z elektrodą o potencjale pływającym. Aktuator ten zastosowano do aktywnej kontroli przepływu wokół elementów aerodynamicznych. Rezultaty badań wskazują, że badany aktuator umożliwia kontrolę oderwania warstwy przyściennej wokół modeli skrzydła NACA 0012 i NACA 0015.