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An accurate estimation for the magnetostrictive effect in highly grain-oriented electrical steel sheet (HGO-ESS) is helpful for determining the deformation and vibration originating from magnetostriction during the design stages of electrical equipment such as the motor and power transformer. In this paper, a Preisach-based magnetostriction model for HGO-ESS is proposed to simulate the normal and shear magnetostriction properties under alternating and rotating magnetic fields. In the model, the Everett function databases are constructed and identified by using a set of measured symmetric magnetostriction butterfly loops under different rotating magnetic field conditions. The measurement butterfly loops are measured by a round-type two-dimensional single strain tester (R-2-D-SST). Finally, the simulation data and measurement data under different rotational magnetization conditions are compared to verify the effectiveness of the proposed model.

In this study, Leibniz algebras and the derivations and properties of Leibniz algebras were given, respectively. The stable automorphism group of explicit splitting extension was calculated via the stable automorphism group of Abelian extension of finite group splitting. Based on the stable automorphism group of the splitting extension studied, the non-Abelian extension and the second order non-Abelian co-homology group of Leibniz algebra were investigated in detail according to the stable automorphism group of the splitting extension.

In order to predict the performance of designed electric machines, and also based on which the high efficiency of the drive systems can be obtained, the accurate calculation of the iron loss is necessary. Taking modeling accuracy versus modeling complexity into account, this article proposes a general and accurate iron loss calculation method considering harmonics based on the loss surface (LS) hysteresis model and finite-element method (FEM). Compared with the previous triangular wave excitation, this article uses the data under sinusoidal wave excitation to establish the LS model, which is more convenient for engineering application. A specimen is tested for different flux densities with harmonics, the extensive results verify the modeling method. Due to a powerful hysteresis model, the iron loss calculation can be realized by the direct integration of hysteresis loops. A separated iron loss calculation package is developed, and it is combined with the commercial finite-element software to compute the iron loss distribution. The method that combines the LS model and FEM is proved feasible by comparing the calculated iron loss with the measured one for the Epstein frame.

This study introduces a new structure of the magnetic lead screw (MLS) intended for wave energy conversion (WEC) applications. One of the key challenges in the application of MLS technology for wave energy lies in the manufacturing of its complicated ideal helix. Structural simplification and processing technology are quite essential in promoting the development of the magnet screw. This study proposes a new method for shaping the desired ideal helix in a simple way with parallelly magnetised magnets. This simple structure reduces manufacturing complexity while maintaining good force density. The magnets with parallel magnetisation are also easier and cheaper to manufacture than the magnets with radial magnetisation. A prototype is manufactured and tested in the laboratory. In addition, the electromagnetic performance of the new structure is evaluated as compared with the magnet screw with ideal helix using the three-dimensional finite element analysis, verifying the advantages of the proposed structure.

Akaike information criterion (AIC) and corrected Akaike information criterion (AICc) are two widely used information criteria. It is well known that neither of them is consistent because there is a...

This paper presents an identification algorithm of the scalar Preisach model by using a set of symmetric minor hysteresis loops and suggests an improved vector Preisach model to describe the vector and anisotropic hysteresis behavior of a non-oriented (NO) electrical steel sheet (ESS) under rotating magnetic fields. Symmetric minor hysteresis loop is quite easy measured, so an identification algorithm based on symmetric minor hysteresis loop instead of first-order reverse curve is presented in this paper. The vector Preisach model employs a nonlinear coefficient, which is a function of magnitude and a direction of magnetic flux density, to describe the anisotropic property of the NO ESS and increases the numerical accuracy. The validity of the suggested vector Preisach model is investigated through comparisons with the experimental results under various magnetic field conditions.

A new type magnetic lead screw (MLS) is proposed in this paper. The proposed magnetic lead screw is assembled with a single helix permanent magnet (PM) on the translator, and the rotor adopts double helical PMs which is as same as the traditional MLS. This new structure of magnetic lead screw has many advantages, for example, when the proposed MLS is applied to the wave energy power generation system, and without changing its size, the proposed MLS can not only save a lot of PM consumption, but also adjust its maximum thrust by directly adjusting the width of the permanent magnet to adapt to different sea areas. In addition, the proposed MLS has a higher force density. Finally, compared with the traditional MLS, this new type of MLS also has the advantage of fast startup speed. For the proposed MLS, it is analyzed by the two-dimensional (2-D) finite element method (FEM), since the results of 2-D FEM simulation are almost the same as those of three-dimensional (3-D) finite element method (FEM). Additionally, the 3-D FEM is time-consuming. To verify the advantages of the proposed MLS, the performance of the proposed MLS is compared with the traditional MLS and the reluctance-based MLS (RBMLS). At last, the impact of different important parameters on the performance of the proposed MLS are analyzed. It provides a new option for the application of MLS in wave energy power generation systems.

Smart Transformers (ST), which is a power electronic-based transformer with control and communication functionalities, can provide an effective solution to overcome the challenge of future grids. Battery energy storage systems (BESS) are indispensable to compensate sudden variations in the power generation from the renewable energy sources (RES). This paper proposes a current-fed quadruple active bridges (CF-QAB)-based cascaded H-bridge smart transformer architecture, which not only play the role of power electronic transformers, but also achieve the integration of BESS in an electric distribution system. The advantage of the proposed architecture is requiring no additional hardware circuits, which reduces system volume and cost with respect to the existing ST architecture.

The point-absorber-type Wave Energy Converter (WEC) is regarded as one of the most promising forms to convert wave energy into electricity. In this paper, a new global maximum power point tracking (MPPT) control strategy based on the PSO algorithm is proposed to extract the maximum power for the point-absorbing type WEC. Firstly, a mathematical model of the point-absorber-type WEC based on hydrodynamic theory is proposed. In the model, the maximum power extracted state is related to the two parameters RPTO and XPTO. These two parameters are related to the characteristic of the wave and the system and are difficult to obtain directly. Therefore, the above parameters are identified by the particle swarm optimization (PSO) algorithm to seek the maximum power point. A given irregular wave is applied to the model to verify the effectiveness of the strategy. In additional, to verify the advantages of the MPPT strategy based on PSO, the proposed strategy is compared with that bases on the Flower Pollination Algorithm (FPA) algorithm.

The cascaded H-bridge (CHB) multilevel converter is a promising topology for large-scale photovoltaic (PV) systems. However, the different PV panels may generate different power, which results in the inter-module and inter-phase power imbalance. Consequently, the over-modulation caused by the inter-module and inter-phase power imbalance is one of the key issues for the CHB-based PV system. This paper analyzes the theoretical constraints on system operation range caused by power imbalance and discusses the necessary and sufficient condition to achieve complete power balance in modular cascaded PV systems based on graph-theory model. According to the graph-theory model, several derivate topology structures are presented and the basic simulation and experimental results are shown to verify their power balancing ability.

In order to balance the instantaneous power difference between DC and AC, many non-isolated micro-inverters with power decoupling have been proposed, where long-life and small-capacitance film capacitors can be used instead of short-life and large-capacitance electrolytic capacitors. However, these non-isolated micro-inverters must use additional switches and still encounter common-mode current problems. In this article, a novel non-isolated micro-inverter is proposed, which simultaneously achieves Electromagnetic Interference (EMI) common-mode current suppression and active power decoupling with a minimum number of switches. Simulation has verified the good performance of the proposed non-isolated micro-inverter.

In the power electric based power system, the grid impedance may change over time, which seriously affects the control and stability of the grid-connected converters. The existing methods usually had used Kalman filter method to detect the real grid impedance in real time. However, there is always a certain error between the estimated result and the true value. This article first establishes the Kalman observation model, and then analyzes the reason for the Kalman filter observation error. In order to eliminate the Kalman filter observation error as much as possible, a new method of predicting the grid impedance error, that is, the univariate linear regression method, can make the grid impedance value more accurate. Simulation has verified the effectiveness of the method.

Magnetic lead screw (MLS) owns many merits for wave energy generation system applications. However, to resist the huge, instantaneous impact of the waves, the radius of the mover and rotor of the MLS should be large to obtain sufficient stiffness. And the length of the mover needs to match the height of the wave to transfer as much power as possible. Therefore, a great many of permanent magnets (PMs) will be consumed when size of the traditional MLS is huge, and the maximum thrust force would be much greater than the wave excitation force. This will lead to the waste of PMs and poor starting performance. Also, the ideal spiral PMs are quite difficult to manufacture. Therefore, in this paper, a novel type single-helix MLS, which adopt single spiral PMs on the surface of the rotor and translator, is proposed to save PM consumption on the premise of meeting the demand of wave power generation system. The new structure provides a new choice for the application of magnetic screw in wave power system. The performance and the design features of the proposed novel MLS is analyzed through the three-dimensional finite-element method and compared with the traditional MLS and reluctance-based MLS. In addition, a simple spiral PM installation method based on discretized PMs for the proposed MLS is also proposed in this paper.

A reluctance lead screw (RLS) is proposed in this paper which consists of a rotor and a translator, forming a magnetic device that is able to transfer low-speed linear motion into high-speed rotational motion. Permanent magnets (PMs) are only installed in the rotor, making it more suitable for long-stroke applications. The design aspects are assessed by finite element analysis (FEA) and the performance is evaluated. In addition, the thrust force per magnet volume is presented for evaluating the utilization rate of the PMs. The simulation results show that RLS has an advantage in terms of the PM utilization rate. A new method for realizing spiral magnets has also been developed which can not only reduce the manufacturing difficulties, but also ease the installation work. Finally, based on the simulations and analyses, two RLS prototypes designed for wave energy converters (WECs) are presented to show the potential applications of this novel topology.

Summarization: In grid-tied DC/AC inverter applications, the equivalent grid impedance often varies widely, which may limit the bandwidth of the inverter control system. This paper introduces a new method to perform the online estimation of the equivalent grid impedance with a Kalman filter by observing the grid voltage and grid current, as well as the voltage at the point of common coupling (PCC). With the estimated grid impedance, a high control bandwidth can be achieved for the grid-tied inverter through online regulation of the proportional coefficient of a current controller. A MATLAB/Simulink model of a grid-tied single-phase inverter has been setup to demonstrate the effectiveness of the proposed method. The simulation results show that the online estimated impedance is accurate enough and the inverter system can continuously maintain a high bandwidth, even under weak grid operating conditions. Παρουσιάστηκε στο: The 46th Annual Conference of the IEEE Industrial Electronics Society

This paper presents a simple dynamic vector-play model to calculate the iron loss and describe the vector hysteresis behavior of a non-oriented (NO) electrical steel sheet (ESS) under 50 Hz rotating magnetic fields. Based on the iron loss separation theory, the proposed model is separated to the static hysteresis component and eddy current component. The static hysteresis component is constructed by vector play model, which is identified by using 1 Hz minor $B$ – $H$ loops. And two coefficients $\omega _{x}$ and $\omega _{y}$ are introduced to consider the anisotropic property of NO ESS and the excess loss of eddy-current component under 50 Hz magnetic field. The validity of the proposed dynamic vector hysteresis model is verified by comparing it with the experimental results under various 50 Hz magnetic field conditions.

The teaching reform of higher mathematics has been paid much attention and achieved a lot of achievements. But people have not paid enough attention to the exercises and homework of higher mathematics. The exercises and homework of higher mathematics should not be ignored. It is an important aspect of teaching and learning of higher mathematics. The traditional higher mathematics homework is the students’ personal operation to do the exercises in the textbook after class. Practice has proved that these exercises are very necessary, but it is far from enough for homework to be limited to such exercises. In order to stimulate students’ interest in learning, encourage their confidence in learning and strengthen the spirit of cooperation among students, the structural design under the background of information is mainly adopted in enriching the forms of higher mathematics homework.

This paper presents an improved identification algorithm of the scalar play model, and suggests a novel vector play model to describe the vector hysteretic behavior of a nonoriented electrical steel sheet (ESS) under rotating magnetic fields. The proposed identification algorithm gives much better numerical accuracy than a conventional one by assigning more play operators than the measured asymmetric minor loops. The vector-shape function of the suggested vector play model consists of two scalar shape functions, which are independently identified by using measured hysteresis loops under alternating magnetic fields along rolling and transverse direction of ESS, respectively. The vector play model, furthermore, employs a nonlinear coefficient, which is a function of the magnitude and direction of magnetic flux density, to increase the numerical accuracy. The validity of the suggested vector play model is verified by comparing it with experimental results under various magnetic-field conditions.

To maximize the generated output power under random waves, the control strategy of maximum power point tracking (MPPT) is incorporated in point-absorbing type wave energy converter (WEC) system. However, due to the influence of mutative wave conditions, the curve of the maximum average power appears in multiple peaks, adding complexity to the tracking process. This paper proposes a new MPPT control technique for a wave power generation system, by using the flower pollination algorithm (FPA) instead of the conventional hill-climbing method. Compared with the hill-climbing method, this method has advantages of achieving a smaller peak-to-average ratio and capturing the more average power under the same sea state. The verification has been carried out through the simulations and the experimental results on a lab test bench.

This paper proposes a new measuring system and an improved model for magnetostriction characteristics of a highly grain-oriented electric steel sheet (HGO-ESS) whose magnetic domains are bigger in size and higher in the degree of alignment than those of a grain-oriented one. The measured data of anisotropic magnetostriction characteristics of the HGO-ESS, through an improved model that has its theoretical basis on the mechanical elasticity, are included in the finite-element analysis of magnetostriction force of a power transformer. The effectiveness of the measuring system and improved magnetostriction model is validated by comparing with the experimentally measured results over a 30 MVA power transformer model.

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This paper proposes a new Wave Energy Converter (WEC) extremum-seeking control method using Flower Pollination Algorithm (FPA) to achieve the maximum power absorption. This method can absorb the maximum power from the wave energy as well as the reduced Power Peak-to-Average Ratio (PPAR). Different from the existing methods, the proposed one does not depend on the dominant frequency of irregular waves, the accurate knowledge of excitation force, and WEC parameters..

After binding by acetylcholine released from a motor neuron, a nicotinic acetylcholine receptor at the neuromuscular junction produces a localized end-plate potential, which leads to muscle contraction. Improper turnover and renewal of acetylcholine receptors contributes to the pathogenesis of myasthenia gravis. In the present study, we demonstrate that endoplasmic reticulum (ER) stress contributes to acetylcholine receptor degradation in C2C12 myocytes. We further show that ER stress promotes acetylcholine receptor endocytosis and lysosomal degradation, which was dampened by blocking endocytosis or treating with lysosome inhibitor. Knockdown of ER stress proteins inhibited acetylcholine receptor endocytosis and degradation, while rescue assay restored its endocytosis and degradation, confirming the effects of ER stress on promoting endocytosis-mediated degradation of junction acetylcholine receptors. Thus, our studies identify ER stress as a factor promoting acetylcholine receptor degradation through accelerating endocytosis in muscle cells. Blocking ER stress and/or endocytosis might provide a novel therapeutic approach for myasthenia gravis.

This paper proposes a new iron loss calculation algorithm taking rotating magnetic fields into account by incorporating a vector stop model and one-dimensional finite element analy of eddy current distribution. The algorithm is applied to a non-oriented material 35PN440, and its results are compared with conventional and the measured ones.

To solve the problems which happened in Mobile IPv6 fast handover such as handover latency, high packet loss and other, we propose a mobility management model called ESMIPv6. The model in SMIP basis is based on the user moves; the model created the user moves curve to forecast the user mobility model, while simplifying the structure of the SMIP. The design goal is to reduce the handover latency by forecasting the user moves, so as to eliminate the connection is interrupted and the signaling load minimum.

Summarization: The power supply system design of a marine data buoy system is a challenge. Due to cost reasons, it is difficult for marine buoys to obtain electricity directly from the power grid. At present, marine buoys use solar energy, wind energy or wave energy to supply power to sensors. Among them, the employment of wave energy and solar energy has broad application prospects due to the complementary power production of these sources. This paper presents a new wave energy conversion (WEC) device for a marine buoy, which is composed of a floating body and a power generation device. In addition, a three-dimensional finite element simulation model of the buoy movement is established, and the simulation is carried out using hydrodynamic software. On the basis of simulation, experiments are carried out on a 50 kg core power generation unit to estimate the power generation performance of the proposed WEC device. Παρουσιάστηκε στο: 47th Annual Conference of the IEEE Industrial Electronics Society