Wyniki 1-4 spośród 4 dla zapytania: authorDesc:"Serge OLSZEWSKI"

Optical emission spectroscopy investigation of the low-power multispark plasma actuator


  Surface discharges like surface sparks [1] and dielectric barrier discharge (DBD, [2,3]) has large number of industrial applications and has been a subject of research for at recent years. Despite the fact that many studies have been carried out to understand the physics of DBD and other surface discharges’ behavior, some important issues are still far from being clear. In this review, some recent works related to the basics of surface discharge physics and innovative concepts of discharge behavior that were discovered recently. Gas discharges burning near the solid surface containing the electrodes have been investigated recently for many practical applications. Among them, there are: treatment of hydrophobic polymer and polycarbonate surfaces [4], creation the efficient exciplex sources of radiation [6], low-temperature plasma (LTP ) treatment of the wool fabrics [7], oxidation of the organic materials [8], modification of the polymeric powder capillarity [9], steam reforming of methanol (SRM) for hydrogen production [10], benzene conversion in air [11], ozone production [12], production of thin organic powder [13] and increasing the efficacy of UV radiation for the plasma display panel (PDP) dielectric cell [14]. In the most of that works, discharge influence on the gas flow in the nearby region, is the one of the main result. Articles [3, 15-19] and many others are specially devoted to the study of plasma actuators that applies the surface discharges for the control of gas flow near the surface where electrodes are located. The work [19] was demonstrated that actuators constructed with thick dielectric material of low dielectric constant produce a body force that is an order of magnitude larger than that obtained by the traditional actuators. These new actuators allow operation at much higher applied voltages without the formation of discrete streamers which lead to body force saturation. Optical emission spectroscop[...]

Modeling of the acoustic field of a multi-spark plasma actuators


  class of technological applications. It is, for example, sources of UV radiation [1]. It?fs a different kind of high switching discharge devices [2]. One of the possible uses arrays of sparks may be to create devices that control the aerodynamic flow in different areas of the wing aircraft. Such devices using an agent influence the discharge plasma are called plasma actuators [3]. One of the physical factors that affect the conditions of vortex shedding in the turbulent flow around the surface can be acoustic pressure shock wave generated by a spark discharge. However, the spatial distribution of the acoustic field of distributed point sources in non-linear approximation has been studied insufficiently. Actuality of this problem may be called also in the sphere of information protection. It is known [4], to provide the privacy of information transmitted acoustic channels from unauthorized access by means of special devices, using artificially induced acoustic noise field. However, if use of the noise field which has a low acoustic power as compared with the desired signal, that existing methods for mathematical processing of the data [5] isolated analyzed signal against the background of such interference. Using the noise fields that have an acoustic power that exceeds the capabilities of existing signal processing usually leads to a loss of desired signal for the consumer too. In view of these considerations, the direction on the use of overwhelming noise is self-contradictory. One of the ways out of the current controversy may be a synthesis of stationary spatial sound field with local interference zones reduced acoustic power. Therefore, the task of creating a numerical model for the calculation of the acoustic fields generated by discrete spatial patterns of sparks is an important and relevant. The present work is devoted to constructing of such a model, which takes into account the non-linear propagation of acoustic wav[...]

Experimental research and modeling of plasma torch of direct-flow plasmatron with a transverse arc


  Sources of non-equilibrium atmospheric pressure plasma play an increasingly central role in various plasma-chemical technologies. This is destruction of toxic high-molecular compounds in aqueous solutions [1], this is reforming of hydrocarbons in synthesis gas [2], and the creation of nano-materials with organic liquids [3]. When created plasma-chemical wastewater treatment technologies from toxic pollutants leading objective is to develop a low-power atmospheric pressure plasma sources with larger active zone volume compared with spark or arc discharge. Typically such sources are plasmatrons of various designs. The active plasma volume of these plasmatrons is the torch that formed by gas-dynamic flow. One of the methods for obtaining of nonequilibrium plasma can be to create low-power arc plasmatrons with the buffer gas is blowing across the lines of electric current. To date, is accumulated sufficient experimental material that demonstrates high prospects of using transverse arch, due to its unique physical and chemical properties. In [4] it is shown that arc plasma becomes nonequilibrium due to the interaction with the gasdynamic flow. However, a clear physical picture of the spatial distribution of the flow parameters for specific sources of transverse arc is not built. Experimental studies of device of original design named direct- flow plasmatron shown that it is difficult to classify its torch as one of the known types of discharges. This is due to the fact that its structure has several areas with fundamentally different properties. There is a simultaneous coexistence of classic electric arc stabilized longitudinal air flow, transverse arc [5], and secondary discharge between the lateral surfaces of plasmas channel. Detailed experimental studies of plasma parameters of proposed device are difficult, because research object has intricate nature. Therefore, this work was devoted to the analysis of the conditions of form[...]

Throughput physical layer analysis of LTE


  The physical layer performance of LTE in same literature “LTE PHY Performance Analysis under strict 3GPP parameters" [3] and “Receive and Transmit Array Antenna Spacing and Their Effect on the Performance of SIMO and MIMO Systems by using an RC S Channel" [4]. Different values are stated as LTE performance that depends on parameters such as system bandwidth, multi antenna schemes, FDD or TDD operation, etc. The maximum data rate of LTE varies from 100 Mbps to 300 Mbps. There is no sufficient clue of how this value is calculated. The main objective of this paper is to determine and analysis physical layer throughput of LTE Release 8 in different scenarios for uplink and downlink. TDD and FDD operations are considered as separate scenarios in this paper. Based on the system bandwidth that varies from 1.4 to 20 MHz, different amount of physical resources are available during a radio frame. Physical channels and reference signals are mapped to these resources. By calculating the overhead of reference signals that actually do not carry information to higher layers and control channels that convey control information, we can determine the number of resource elements allotted for data transmission. Based on different modulation schemes, code rates, and number of antenna ports, the throughput for data channels can be calculated. In TDD operation there are seven configurations for time domain multiplexing of downlink and uplink data transmission that lead to different throughput values in a given channel bandwidth. LTE Technical Features The main technical features of LTE are presented in [1], including MIMO, turbo coding used in LTE , and HARQ techniques. This paper also presents a performance analysis for 10 MHz of channel bandwidth, MIMO 4x4 and 2x2 in downlink and SIMO1x2 in uplink cases. The downlink control channel overhead is assumed to be 2 OFDM symbols per subframe, and a 0.93 code rate is considered. Based on the[...]

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