In this paper, a numerical analysis was carried out using finite element method to analyse the mechanisms for streamer discharges. The hydrodynamic model was used with three charge carriers equations (positive ion, negative ion and electron) coupled with Poisson equation to simulate the dynamic of streamer discharge formation and propagation. The model was tested within a 2D axisymmetric tip-plate electrodes configuration using the transformer oil as the dielectric liquid. The distance between the electrodes was fixed at 1 mm and the applied voltage was 130 kV at 46 ns rising time. Simulation results showed that the time has a clear effect on the streamer propagation along the symmetry axis. In addition, it was observed that the highest value of the voltage was recorded at 46 ns and the minimum voltage required for insulation breakdown was 112 kV at 200 ns. It was revealed that the streamer velocity recorded the highest value when the streamer reaches the plate electrode and the lowest value when the streamer begins to propagate. Results also showed that the streamer discharge was dominated by positive ions while the negative ions have a low effect.
Calculation of the power density of the nuclear fusion reactions plays an important role in the construction of any power plants. It is clear that the power released by fusion reaction strongly depended on the fusion cross section and fusion reactivity. Our calculation concentrates on the most useful and famous fuels (Deuterium-tritium) since it represents the principle fuels in any large scale system like the so called tokomak.
The varied thermal conductivity (insulation) of silica aerogel with heating for different pH has been investigated, it has been depended on ambient pressure drying method in the preparing silica aerogel samples, also six different pH of samples (1, 2, 3, 7, 8 and 9) were treated under five degree of heating with (50,100,150,200 and 250) ᴼC. This technique is important to test the carry-outs hydrophobic silica to temperature without high-quality material changes in the basic characteristics. The hot-wire technique is used in this work to examine the thermal conductivity, Fourier Transform Infrared Spectroscopy (FTIR) depended to characterize the bonds and their artificial by heating. Resu
... Show MoreThe wind atlas analysis and application program, WAsP, is used to assess wind
energy potential، wind climate from geostrophic winds of a given area. In this paper,
metrological data from Ali Algharby station was used to predict the wind resource
and wind turbine energy production at Ali Algharby site.
Data from metrological station was used to draw up observed wind climates at the
anemometer site. Site contour map was digitized using WAsP Map Editortool.
Observed wind climate, digitized contour map, terrain roughness length, obstacle
groups and their porosity were used as input to the WAsP model. Vestas V182, 1.65
MW turbine was used. Weibull probability distribution graph of wind speed, power
density were dra
Samples of Bi1.6Pb0.4Sr2Ca2Cu3O10+δ superconductor were prepared by solid-state reaction method to study the effects of gold nanoparticles addition to the superconducting system, Nano-Au was introduced by small weight percentages (0.25, 0.50, 0.75, 1.0, and 1.25 weight %). Phase identification and microstructural
characterization of the samples were investigated using XRD and SEM. Moreover, DC electrical resistivity as a function of the temperature, critical current density Jc, AC magnetic susceptibility, and DC magnetization measurements were carried to evaluate the relative performance of samples. x-ray diffraction analysis showed that both (Bi,Pb)-2223 and Bi-2212 phases coexist in the samples having an orthorhombic crystal struct
In this model, we use the C++ programming language to develop a program that calculates the atmospheric earth model from the surface to 250 kilometers. The balance forces theory is used to derive the pressure equation. The hydrostatic equation is utilized to calculate these parameters analytically. Variations of the parameters with altitude (density, pressure, temperature, and molecular weight) are investigated intensively. The equations for gravitational acceleration, sound speed, and scale height are also obtained. This model is used to investigate the effects of the earth's atmosphere on the space shuttle and the moving bodies inside it.
This research provides a study of the virtual museums features and characteristics and contributes to the recognition of the diversity of visual presentation methods, as the virtual museums give the act of participation and visual communication with programs at an open time, so that it would contribute to reflection, thinking and recording notes, developing the actual and innovative skills through seeing the environments. The study has been divided into two sections the first one is virtual museum techniques. The techniques were studied to reach the public and are used remotely by the services of personal computers or smart phones being virtual libraries that store images and information that was formed and built in a digital way and how
... Show MoreIn this paper the research introduces a new definition of a fuzzy normed space then the related concepts such as fuzzy continuous, convergence of sequence of fuzzy points and Cauchy sequence of fuzzy points are discussed in details.
Television white spaces (TVWSs) refer to the unused part of the spectrum under the very high frequency (VHF) and ultra-high frequency (UHF) bands. TVWS are frequencies under licenced primary users (PUs) that are not being used and are available for secondary users (SUs). There are several ways of implementing TVWS in communications, one of which is the use of TVWS database (TVWSDB). The primary purpose of TVWSDB is to protect PUs from interference with SUs. There are several geolocation databases available for this purpose. However, it is unclear if those databases have the prediction feature that gives TVWSDB the capability of decreasing the number of inquiries from SUs. With this in mind, the authors present a reinforcement learning-ba
... Show MoreIn this paper, we define some generalizations of topological group namely -topological group, -topological group and -topological group with illustrative examples. Also, we define grill topological group with respect to a grill. Later, we deliberate the quotient on generalizations of topological group in particular -topological group. Moreover, we model a robotic system which relays on the quotient of -topological group.