Creating a Gain Improvement Technique for a Horn Antenna using a Metamaterial Structure Inserted with a Thin Dielectric Sheet

Objective: This paper proposed a new technique for the metamaterial on the structure of the curved-woodpile Electromagnetic Band Gap (EBG) inserted with a dielectric slab for gain improvement in a conventional rectangular horn antenna. Methods: We described a method to enhance gain by transferring the electromagnetic fields from the aperture of a horn through the EBG structure. Furthermore, we present the design procedures for inserting a dielectric slab into two layers of the EBG structure for the reduction of distance between the horn and proposed EBG structure. Results and Conclusions: Such a proposed technique not only has the advantage of decreasing the total length of the antenna system but also providing higher gain with a low profile structure. This idea has been verified by both simulation and experimental results. The fabricated antenna can achieve 23.9 dBi of gain or higher than the gain, which is obtained using a conventional rectangular horn antenna at around 7 dBi at an operating frequency of 10 GHz. It is apparent that a good qualitative agreement between the measurements and simulations was achieved.

Non-redundant Spherical Near-Field to Far-Field Transformation for a Volumetric Antenna in Offset Configuration

Background: The development of fast Near-Field (NF) measurement techniques allowing the precise determination of the Far-Field (FF) radiation features of an antenna is becoming more and more challenging nowadays. Objective: The goal of the article is the development of an NF To FF Transformation (NFTFFT) with spherical scan for offset mounted volumetric Antennas Under Tests (AUTs) requiring, unlike the classical technique, a reduced set of NF data, that is of the same amount as for the onset mounting case, thus making data gathering faster. In fact, the number of NF data needed by the standard approach may considerably increase in this case, since the size of the smallest sphere surrounding the AUT and centered at the center of the measurement sphere rises. Methods: This goal has been achieved by profitably exploiting the non-redundant sampling representation of electromagnetic field and assuming a volumetric AUT as contained in a sphere. An optimal sampling interpolation algorithm is then employed to precisely reconstruct the input NF data for the traditional spherical NFTFFT from the reduced set of the collected ones. Conclusion: The numerical simulations and experimental tests demonstrate the effectiveness of the developed approach accounting for an offset mounting of the AUT.

Shape Adaptable Medical Multimedia Processing

Introduction:Electronic medical healthcare systems are becoming the backbone of health organizations over the world. The huge amounts of medical multimedia produced by these systems especially images and videos are transmitted by the computer networks that connect these systems. The variability in the shape and texture of transferred medical multimedia data needs adaptable procedures to process these data efficiently. In other words, these procedures must adjust automatically based on the shape of region of interests in the medical multimedia images to cope with fast changes in the healthcare environments. In this paper, we have proposed shape adaptable watermarking approaches for medical multimedia processing systems. The medical images generated by X-rays, MRI and CT modalities are used in our experiments to test proposed approaches. In addition, these approaches were tested under different kinds of signal processing and geometric attacks. The comparative comparison of our proposed approaches with state-of-art approaches proved the superiority and capability of our approaches to adjust the number of selected subands of medical cover image to embed and extract the hospital watermark logos.Background and Objective:The development of an adjustable approach to process medical multimedia signals for healthcare system. The aim of this research is to select adaptably the number of subands of cover image to hide the information of hospital logo watermark inside them such that embedded watermarks can resist different kinds of attacks.Method:The proposed adjustable approach consists of suband selection method, criterion, embedding and extraction procedures, DWT transform, attacks, evaluation metrics,etc.Results & Conclusion:It provides robust and adjustable method to embed and extract watermark logo at different resolution levels of cover medical image and uses with images of different sizes and modalities.

Multilayer Neural Network with Synapse Based on Two Successive Memristors

Introduction: Synapse based on two successive memristors builds the synaptic weights of the artificial neural network for training three-bit parity problem and five-character recognition. Methods: The proposed memristor synapse circuit creates positive weights in the range [0;1], and maps it to range [-1;1] to program both the positive and negative weights. The proposed scheme achieves the same accuracy rate as the conventional bridge synapse schemes which consist of four memristors. Results and Conclusion: However, proposed synapse circuit decreases 50% the number of memristors and 76.88% power consumption compared to the conventional bridge memristor synapse.

Mechanical and Electromagnetic Analysis of High Speed Motor/Generator for Electric Turbo Compounding System

Background: Recently, environment friendly technologies are being introduced as global warming is rapidly progressing. One of the effective way to reduce the problem, Electric Turbo Compounding System has been researched globally. With this system, about 30% exhaust gas can be recycled as a power source. Therefore, this system is effective for engine systems with purposes such as downsizing and increasing efficiency of the system. Objective & Method: Surface mounted Permanent Magnet Motor is applied to this system due to its high efficiency, power density, small size, and low weight. However, during high speed operation, a retaining sleeve is essential in rotor such as Inconel 718 to satisfy a mechanical safety factor of the rotor. In this paper, through basic theory, the sleeve thickness is predicted according to the permanent magnet dimension and minimum sleeve thickness is determined satisfying mechanical safety factor by mechanical analysis. Furthermore, by electromagnetic analysis output characteristics according to the permanent magnet dimension having same constraints such as volume, current density, current and flux distribution are compared. Result & Conclusion: Based on the results of the electromagnetic analysis and mechanical analysis, the appropriate ratio of electric and magnetic loading is determined with equivalent constraint condition. Consequently, only model 2 satisfies the requirement at rated and maximum speed within the current limit.

Experimental Design and Verification of Extended State Observers for Magnetic Levitation System Based on PSO

Introduction: This work presents analysis, design and implementation of two schemes of Extended State Observer (ESO) to estimate the position, velocity and unmeasurable states for magnetic levitation systems, Linear ESO (LESO) and Nonlinear ESO (NESO). The multiplicity of design parameters for both LESO and NESO made it difficult to find appropriate setting of these parameters such that to reach satisfactory performance of observation process. Methods: Particle Swarm Optimization (PSO) technique is used to improve performance of observation process by finding optimal tuned parameters of observer design parameter subjected to specified performance index. Theoretical results of both observers are firstly implemented in the environment of MATLAB/SIMULINK. Then, experimental state estimation of observers is set up based on feedback instrument (33-942S) to verify the simulated results. Results and Conclusion: Root Mean Square (RMS) of estimation error has been used as an indicator to assess the performance of observers. The simulated and practical results showed that LESO could give better estimation performance than NESO.

Battery Losses In a MMC for BEVS Application

Objective:This paper analyses the Modular Multilevel Converter (MMC) topology, where each individual Sub Module (SM), in half bridge configuration, is directly fed by an elementary electrochemical cell.Methods:The aim is to investigate how the reference voltages influence the cells currents waveforms, determining how the active powers and the losses are distributed among the cells. Considering a 2-level Voltage Source Inverter (VSI) topology working in the same conditions, the ratio between the MMC total cells losses and VSI total cells losses is calculated. After showing the system architecture and mathematical model, the cells current waveform investigation is presented and detailed both for triangular and sinusoidal voltage reference waveform.Results:Finally, the results are critically discussed with particular focus on the comparison between the MMC and the VSI topologies.

Design of Power Density Improvement by Applying Novel Shape of Slit and Notch to Outer Rib of Rotor of Spoke-type Permanent Magnet Synchronous Motor

Objective:In this study, improvement of power density by applying novel shape of slit and notch to outer ribs of a rotor that reduces magnetic flux leakage in outer rib and increases air-gap magnetic flux density for spe PMSM for a washing machine, was investigated.Methods:It is important that motors for home appliance require lower manufacturing cost, high power and high efficiency. In order to increase power, rotor shape is re-designed. In the outer rib of the rotor, magnetic flux leakage occurs by permanent magnet and magnetic flux is saturated which is one of the factors that reduces the power and efficiency. However, if the outer rib is designed to be too thin, the permanent magnet may scatter during high-speed rotation. Therefore, a design considering permanent magnet scattering is necessary. Motor for a washing machine has two operating points that washing mode at constant torque point and dehydrating mode at high-speed point.Conclusion:For improvement of higher power density, 2-D finite elements analysis was performed to optimize the parameters of the shape of slit and notch to increase the torque. The torque increases by optimizing width and length of slit shape and notch shape. Finally, with the optimized parameters of shape of slit and notch, stack length was adjusted as per torque requirement for a washing machine motor and power density increases considering the safe factor from stiffness analysis.

Survey of Big Data Role in Smart Grids: Definitions, Applications, Challenges, and Solutions

Objective:This paper provides a literature review on smart grids and big data. Smart grid refers to technologies used to modernize the energy delivery of traditional power grids, using intelligent devices and big data technologies.Methods:The modernization is performed by deploying equipment such as sensors, smart meters, and communication devices, and by invoking procedures such as real-time data processing and big data analysis. A large volume of data with high velocity and diverse variety are generated in a smart grid environment.Conclusion:This paper presents definitions and background of smart grid and big data. Current studies and research developments of big data application in smart grids are also introduced. Additionally, big data challenges in smart grid systems such as security and data quality are discussed.

The Calculation and Optimization Research of Renewable Energy Investment Efficiency under Uncertain Conditions

Background: In the renewable energy investment market, there are risks such as fossil fuel price fluctuations, environmental risks caused by pollutant emissions, electricity price fluctuations caused by energy policies, and so on, which bring certain difficulties to measure the investment efficiency. Methods: In this regard, the paper applies the portfolio theory to the Data Envelopment Analysis (DEA) model to evaluate investment efficiency. First of all, the Monte Carlo method is used to simulate the four uncertain factors of fuel unit price, feed-in tariff, annual operating hours, and carbon price, so as to quantitatively measure the risk and return of different power generation. According to the portfolio theory, it evaluates the portfolio risks and returns, respectively as input and output indicators, so as to build a Data Envelopment Analysis (DEA) model to estimate investment efficiency. Conclusion: The simulation and experimental results demonstrate the effectiveness of the presented method. In details, we select a poor efficiency sample, and then, we propose an optimization measure to improve the efficiency. By adjusting the proportion of its investment, the result proves that increasing the proportion of renewable energy can realize optimization and validity of renewable energy investment. Thus, it provides auxiliary support for the investment decision of renewable energy and realizes the coordinated allocation and efficient utilization of renewable energy.