Majlesi Journal of Electrical Engineering
Volume:15 Issue: 2, Jun 2021

Using metamaterials on the top of the antenna’s accordance to magneto-dielectric superstrate and near zero refraction index theories causesimprovement of radiation efficiency and gain of antennas. In thisarticle, two novel metamaterial unit cells are proposed for gain and bandwidth improvement of Cylindrical Dielectric Resonator Antenna (CDRA). The first metamaterial unit cell is a negative magnetic structure including two rings implemented on both sides of RT/doroid 5880 substrate with dielectric constant of 2.2. Besides, the second metamaterial unit cell is a Double Negative Structure (DNG) realized consisting of two rings printed in one side and a thin wire in other side of RT/doroid 5880 substrate. Two77 arrays of proposed unit cells are considered and used as superstrate layers on the top of a CDRA. Also, the CDRA is made of RT/doroid 6010 material with dielectric constant of 10.2 working at the frequency of 10 GHz. Using proposed metamaterial structures as superstrate layers on the top of the CDRA causesgain and bandwidth improvement up to 3.3 dB and 4.8%,respectively. CDRA in the presence of proposed metamaterial superstrates are analyzed using a 3D full-wave simulator.

Palestine has a large number of remote small communities with no electricity services and the probability of connecting them with local grid in the near future is very poor, because of political and financial issues. This paper will illustratethe techno-economic impact of electrification small communities usingmicro-grid photovoltaic systems, and alsothe CO2 emission that will be reduced in comparative of using diesel generator which pollutes the environment. Theimplementationoftwo micro-grid PV-systems for electrificationoftwo communities in Palestine will coverthe electricity needs of households and street lighting, and can replace candles, kerosene and traditional unsustainable biomass and diesel generators. Beside economic and social benefits, micro-grid PV systems also have positive impacts on people’s health and on the environment due to the reduction of smoke and toxic waste.

The micro-grid operator must provide the energy required by its customers at the lowest cost and consider issues such as greenhouse gas emissions and security. The operator is faced with a multi-objective optimization problem in which customer demand must be provided at the lowest cost and safely. This research provides a new energy management system for islanded micro-grids. The small size of the islanded micro-grids, the high level of intermittentoperationand the low inertia of distributed generation ofinverter energy production resources make the frequency and voltage security two vital factors in the energy management system, which must be managed alongside economic-environmental policies. In this study, two practical tools are provided to help with the optimal operation and increase the profitability of the micro-grid operator. The first tool is the optimal and managed use of the V2G mode of electric vehicles. In the proposed approach, not only the penetration of electric vehicles in the network is managed but also this equipment is used to solve some of the network's challenges. The second tool is responsive loads and demand response programs in order to achieve the goals of the micro-grid operator. Covering the uncertainty of renewable energy sourcesby responsive loads, and how to model a demand response program in a micro-grid, arefollowed in this study.The strategy pursued several goals, including reducing energy and load costs, reducing the cost of charging EVs, and improving network parameters and security, such as voltage and frequency.The results confirm the effectiveness of the proposed approach

One of the essential pieces of equipment in the power system is the Automatic Voltage Regulator (AVR) or synchronous generator excitation. The system's goal is to maintain the terminal voltage of the synchronous generator at the desired level. AVR is inherently uncertain. Hence, the proposed controller should be able to handle the problem. In this paper, Fractional Order Fuzzy PID (FOFPID) controller has been employed to control the system. To enhance the controller's performance, the Grasshopper Optimization Algorithm (GOA) is used to tune the controller's parameters. Unlike other methods, the FOFPID controller gains are not constant and alter in different operatingconditions. The robustness of the controller has been investigated, and the comparative results show that the proposed controller has a better performance against other methods

In this paper, electromagnetic (EM) scatterings from electrically large Perfect Electric Conductor (PEC) and Perfect Magnetic Conductor (PMC) targets coated with Uniaxial Electric Anisotropic Medium (UEAM) layer are evaluated and compared. The effect of the coating layer’s parameters including εu, εvand the thickness (d) are studied. It is shown that radar cross section (RCS) of a PMC with UEAM coating is less than that of PEC with the same coating. In some cases, about 20 dB reduction in RCS hasbeen obtained for UEAM coated PMC plate

In this paper, a Zero-Voltage Transition (ZVT) non-isolated high step-up multi-input DC-DC converters is proposed which employs anauxiliary cell and diode-capacitor multiplier. The auxiliary cell has only one switch and is suitable for high step converters with diode-capacitor multiplier. In the proposed converter, all semiconductor devices operate under fully soft switching condition. The main switches turn on and turn off under Zero Voltage Switching (ZVS) condition whereas the auxiliary switch turns on under Zero Current Switching (ZCS) condition and turns off under zero Voltage and Zero Current Switching (ZVZCS) condition. Also, ZCS condition at turn-off is provided for all diodesto eliminate reverse recovery issue.The structure of the proposed converter includestwo boost cells, one diode-capacitor multiplier cell, and one ZVT auxiliary circuit. Soft switching conditions for all main switches are provided by only one auxiliary circuit.The proposed converter has high step-up conversion gain without any coupledinductor. Soft switching conditions, continuous current of input sources, high efficiency,expansion capability of input sources,returning the energy of the auxiliary circuit to the diode-capacitor multiplier and low-voltage stress on switches are the main advantages of the proposed converter. The steady-state analysis of the converter and operation modes are discussed. A 160-W prototype of the proposed converter is designed and implemented.Experimental results confirmthatthe theoretical and the efficiency of the proposed converter reaches 96.4% at the nominal load

Blumlein discharge circuit stores electrical energy in its transmission line and canreleasethisenergy within a few nanoseconds. This leads the Blumlein to discharge circuit for many applications ranging from electrical discharge in the air to generate nitrogen laser, excitation source for vaporlasers to sub-nanosecond avalanche drivers.In this letter, we have simulated the equivalent Blumlein discharge circuitin Multisimulation and compared the results with the analytical modelto have the insight ofvariations of voltage, current and power in the Blumlein circuit. The Blumlein circuit isdivided into spark gap (spark gap)and Blumlein transmission linesections to observe the voltage, current and power oscillations.The rapid oscillations of voltage across the spark gap initiatethe discharge in the long transmission lines of Blumlein thatgenerates the coherent UV pulses.This study could pave the way towards the generation of ultraviolet (UV) pulses in the air at the atmospheric pressure.

Due to the increasing number of cores in a chip, electronic networks on chip cannotbe an effective solution for using multi-core processors. The use of optical connection technology for networks on 3D chip is an ideal choice recommended in response to delay and reliability.In optical network architecture on 3D chip, 7-port routers are used to data transfer. The structure of the optical routers in the network on the 3D optical chip affects the Performance transmission of the entire network so that the provision of optical router with minimal loss and power consumption is considered by researchers in this domain.In this study, a seven-port Non-blocking optical router based on the Mach Zehnder interferometer optical switch in the network on a 3-D optical chip is presented. This router consists of 18 Mach Zehnder interferometer optical switches that can transfer multiple wavelengths concurrently.To evaluatethe proposed 7-port router in the network on the 3D optical chip, the parameters of insertion loss, bandwidth density and power consumption are considered and the simulation results represent that this router decreases the loss as much as possible and improves the use of the wavelength channel comparing to available router and has the ability to transfer 4 wavelengths simultaneously with a wavelength range of 1525-1565 nm and a data transfer rate of 20Gbps for all 42 optical links. So it is useable for optical connection on the chip.