Free space optical communication systems are the future of the communication systems which can meet the needs of the end users who are demanding high bandwidths to support high-speed communication. These merits are due to its numerous advantages as well as their better performance. This paper studies the effect of environmental parameters like rain, fog, haze, snow, and dust on the performance of optical wireless communications using Opti-system program. This work considers the effect of visibility as well as operating wavelengths on atmospheric attenuation in different weather conditions for free space optical link. For different weather conditions the max distance between transmitter and receiver can also be estimated. The system analysis depicted the better performance of the Multi-Input/Multi-Output (MIMO) configurations compared to Single Input/Single Output (SISO) at different weather conditions.
<p>Attempting to reduce the existing electricity consumption bill, as well as the stability and non-outage grid recharge with the lowest possible cost and suitable quality, is one of the most important goals for those interested in energy around the world. This paper study the circumstances surrounding the Egyptian society to find the best solutions to a achieved this goals, and it was found that solar energy is one of the best alternatives available for energy. Firstly will be study the electricity consumption bill, slice prices and a program was made to calculate the consumption invoice moreover another program for quick estimation to the proposed solar system.The proposed system provides a smart integration between the solar system and grid, where the supply sustainability and the optimal cost are considered. This configuration allows the two sources separately or simultaneously supply the loads depending on photovoltaic extracted energy. Operational analysis of the proposed system will discussed in this paper. The proposed system consists of solar cells, charge controller, batteries and inverter plugged to automatic transfer switches (ATS) using Programmable Logic Control (PLC). The system grantee a safe and reliable load feeding independently on the grid status. The system durability is the most depicted feature through the modelling and experimentally results. A typical case studies for about four years of non-outages photovoltaic-grid hybrid supply (the implemented system) will be presented and discussed.</p>
Augmenting the electrical systems reliability can be accomplished by earthing every stage of electricity generation, transmission and utilization. An accurate grounding system resistance calculations recommend to consider the relevant realistic effective parameters. This paper demonstrates the effect of these parameters such as soil types, soil moisture status in terms of the ambient temperature and finally the earthing electrode types and dimensions. This study comprises the common soil moisture statues such as frosty, cool, wetted, liquid, worm or dries for each of boggy, clay, sandy, silty, peaty, chalky, loamy soils. Moisture proportion varies in these soil types that could lead to diversity of soil resistivity.Full description of earthing resistance profile in case of the different soil types, different environmental conditions as well as different electrode types will be presented. Individual MATLAB files for the different electrodes types will be developed. This work extends the soil moisture states and their effects throughout the whole earthing calculations. The system point by point results are in successfully agreements with the corresponding ETAP results. Keywords :Earthing system, electrodes, moisture, touch, step voltages, and fault cur rent. INTRODUCTION Grounding is predominately the connection between an electrical system and general mass of earth, the last being soil volume, rock and so on, dimensions are extensive in contrast with the electricity system. It is significant that, in Europe they tend to utilize the expression "Earthing" while in North America, the expression which is more common being "Grounding". The purpose of earthing in electric power facilities is to ensure effective protection of people and animals from injuries inside and outside the substation, as well as technical protection of expensive equipment in power substations. The human being protections, the building safety and the systems life time are always occupying the highest priority of the earthing systems designers concern [1-3]. The earthing systems, in fact have several different topologies. The classifications of these are broadly based on each of: Earthed system (power station, hybrid power station, residential homes or appliances). Earthing platforms (electrodes, soil and the environmental parameters). This work high light on the earthing parameters for a wide grounding dynamic range where all earthing electrodes (single rod, multi-rods and grids) can be used. Widest range of the temperature changes, as well as the excepted different soil types are considered. Grounding system calculations However, the high credibility of IEEE std-80 to calculate discretely the grounding resistance for different grounding topologies, the proposed calculations validate a complete resistance description in term of the whole grounding parameters. Summarized analytical calculations of the most dominant ground schemes are listed as follows: Single rod The single ground rod of fig.1, could offer the cheapest and most convenient means...
The direction to enhance the electrical, dielectrica and mechanical characteristics of insulating materials used in cables has become essential in order to plan new insulation systems used in the nuclear power plant. The current study is to investigate the improvement in these properties of Cross-linked polyethylene (XLPE) due to the addition of clay nanoparticles. The XLPE/Clay-Nanocomposites, with different weight fragments of nanoparticles up to 5 %, were fabricated using the mixing of XLPE with the aid of nanoparticles dispersion within the melted polymeric matrix. The irradiation experiment was performed on both the pure XLPE cable insulation and the filled one, by using 60 Co gamma-ray source with an irradiation dose rate of 1.87 KGy/h at 50 o C temperature of the chamber. The surface morphology of synthesized XLPE / Claynanocomposites was characterized by Scanning Electron Microscopy (SEM) and the dielectric and mechanical properties were measured. It is found that the breakdown strength of XLPE / Clay was increased with incorporating clay nanoparticles into their matrix compared to that case of unfilled XLPE. This reveals that XLPE / Clay-nanocomposites had better electrical properties, 1 % was found the optimal loading fraction of clay nanoparticle. This may be referring to the low surface energy of the clay nanoparticles that prevented the agglomeration of nanoparticles and repressed the free space charges resulting in a decrease in the capacitance and losses inside the nanocomposites. Furthermore, both electrical capacitance and dielectric constant are increased by about 20%, for the XLPE / Clay at 50 KGy compared to pure XLPE at 1% (the optimal loading fraction). Also, it is found that the optimal loading fraction of clay nanoparticle is 4% for improved mechanical properties in XLPE cable insulation.
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