International Journal of Applied Electromagnetics and Mechanics - Volume 44, issue 1

Authors: Yang, Fan | Zhong, Jie | Zhao, Gen | Liu, Xinghua | Ran, Wei | He, Wei

Article Type: Research Article

Abstract: More and more ultra-high voltage (UHV) transmission line will be built in China, and the design of external insulation is critical for the safe operation of UHV transmission line. Air relative humidity (RH) and temperature can affect its permittivity and electric field around the transmission line, hence in the paper the numerical relationship between the electric field, air permittivity and air temperature, RH is investigated by field measurement test and numerical analysis. Firstly the measurement tests …are setup to measure electric field strength and atmospheric parameters, in which the electric field, air temperature and RH at same measuring point are measured repeatedly on different days. Then scatter plots are used to reflect the relationship between field strength and temperature along with relative humidity intuitively, and correlation analysis is conducted on the measurement data. Finally the numerical model for the electric field and air RH & temperature, numerical model for the air permittivity and air RH & temperature are obtained. The results provide reference for UHV external insulation design to improve their operation stability and performance. Show more

Keywords: Power frequency electric field, air permittivity, temperature, relative humidity, correlation

DOI: 10.3233/JAE-131730

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 1-16, 2014

Authors: Yang, Xiaoqing | Sun, Di | Zuo, Teng | Chen, Xu | Huang, Kama

Article Type: Research Article

Abstract: To improve the gain of microstrip antenna, it can be realized by artificially introducing metamaterials into microstrip antenna. This paper introduces four kinds of metamaterial structures, such as dendritic-type, cross-type, s-type and h-type. All can improve the antenna performance in varying degrees. Based on the analysis and comparison of the simulated results, we found that the dendritic-type metamaterial microstrip antenna has the most remarkable influence on increasing of the antenna gain with the bandwidth …basically unchanged. At last, the simulated results were compared with the measured results. The good agreements can be observed. Show more

Keywords: Antenna, gain, metamaterials

DOI: 10.3233/JAE-131731

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 17-25, 2014

Authors: Li, Xi | Yang, Lin | Hou, Jia | Guo, Yan-Ping | Gong, Chen

Article Type: Research Article

Abstract: The analysis and design of a dual-band unequal Wilkinson power divider are presented in this paper. A structure including isolation stubs is proposed in order to reduce the parasitic effects between the two stubs that are connected by the isolation resistor. The design parameters of the dual-band unequal power divider are presented in explicit closed form. The validity of this analysis is confirmed through the design, simulation, and experimental results with a power divider for 1 …and 2 GHz. Show more

Keywords: Dual-band, unequal power divider

DOI: 10.3233/JAE-131732

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 27-31, 2014

Authors: Tang, Enling | Xu, Hongjie | Wang, Meng | Zhang, Qingming | Li, Zhiqiu | Xiang, Shenghai | Yang, Minghai

Article Type: Research Article

Abstract: In order to study the critical collision speed of light flash generated by strong shock natural dolomite plate, we use optical fiber transient pyrometer combined with the two-stage light gas gun loading system, the strong shock experiments were performed under four kinds of experimental conditions. Each experiment used 1 set of optical fiber probe, and optical fiber probe is installed directly at the collision point. The relationships between light flash intensity and time are obtained through …the experimental original data and calibration. The experimental results show that the light flash intensity gradually weaken with collision speed decreasing under the given experimental and optical fiber probe arranged at the incident angle of 45° and the wavelength range of 550–700 nm. Finally, the critical impact velocity of light flash produced by strong shock dolomite plate is between 1.6 and 1.7 km/s. Show more

Keywords: Strong shock, impact light flash, pyrometer, light flash intensity, critical impact velocity

DOI: 10.3233/JAE-131733

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 33-39, 2014

Authors: Lee, Sang-Yub | Ro, Jong-Suk | Jung, Hyun-Kyo

Article Type: Research Article

Abstract: For a permanent magnet machine, temperature rise due to the losses in the rotor can affect the performance of the permanent magnet. This is a critical problem for the designers of electric machine. These losses, especially eddy current losses in the conductive part of the rotor, cause heat which cannot easily be mitigate due to the mechanical structure. Therefore, it is very important to consider the losses in the designing step to ensure that the machine …operates stably. The most common technique of reducing the eddy current losses is to divide them into smaller parts. The analysis for this segmentation structure is only possible in 3D-FEM (Finite Element Method) and though this requires a considerable amount of time during design step. Therefore, it is necessary to calculate the eddy current losses rapidly and accurately. In this paper, an eddy current loss analysis method in the retainer of the permanent magnet machine which has a high power density is proposed. First, the concept of effective conductivity is introduced to solve the segmentation problems not to use 3D-FEM. Also, in order to improve the accuracy of the proposed method, the skin effect which occurs in high speed driving region is considered and a FFT analysis is also performed on the harmonic components of air gap flux density. Finally the thermal analysis result which is based on the loss analysis result is also demonstrated and it is verified to compare with the thermal experimental results. Show more

Keywords: Eddy current loss, experimental results, permanent magnet, permanent magnet machines, retainer, skin effect, thermal analysis

DOI: 10.3233/JAE-131734

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 41-50, 2014

Authors: Tang, Enling | Xu, Hongjie | Wang, Meng | Zhang, Qingming | Li, Zhiqiu | Xiang, Shenghai | Yang, Minghai

Article Type: Research Article

Abstract: To investigate light flash produced during hypervelocity impact in the laboratory, we have conducted a series of experiments on a two-stage light gas gun at different impact velocities and the same impact angle. Light flash were acquired through optical fiber pyrometer measurement system during the whole physical process in hypervelocity impact, Experimental results showed that the maximum light flash intensity decreases with impact velocity increasing, and maximum light flash intensity should exist a critical impact …velocity for polycarbonate projectile impacting natural dolomite plate, which may be between 2.52 km/s and 4.21 km/s at the wavelength of 550 nm–700 nm. In addition, the light flash intensity peak value was 0.4 ∼ 0.5 mW.cm^{-2} .nm^{-1} in the experimental conditions in the paper. Show more

Keywords: Hypervelocity impacts, polycarbonate projectile, light flash, dolomite, pyrometer

DOI: 10.3233/JAE-131735

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 51-58, 2014

Authors: Khalid, Muhammad | Syed, Aqeel A. | Naqvi, Qaisar A.

Article Type: Research Article

Abstract: Electromagnetic scattering by a circular cylinder, characterized by D'B, DB' and D'B' boundary conditions, is studied. These boundary conditions deal with the normal components of electromagnetic flux densities and their normal derivatives. Electromagnetic behavior of a circular cylinder satisfying a pair of conditions among these different sets of boundary conditions is first investigated in free space. The response of cylinder placed in free space is discussed for both TM- and TE-polarized incident …fields, with respect to axis of the cylinder. The results are then extended by placing these boundaries in chiral and chiral nihility mediums. Numerical results for these boundaries placed in free space, chiral and chiral nihility mediums are given and compared with those of DB cylinder placed in similar media. Show more

Keywords: Electromagnetic scattering, metamaterials, normal field components

DOI: 10.3233/JAE-131736

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 59-68, 2014

Authors: Yang, Fan | Guo, Xingye | Liu, Xinghua | Dai, Feng | Fan, Lingqiang | He, Wei

Article Type: Research Article

Abstract: The electromagnetic transient can be used to analyze the stability of power systems. In the paper, the electromagnetic transient of an AC-DC interconnected system under different faults is investigated, and interaction between the AC system and DC system is analyzed. Firstly electromagnetic transient models for the components in a high voltage direct current (HVDC) transmission system are presented, including model for converter transformer, harmonic filters, transmission line and control system. Then simulation based …on electromagnetic transient model for a ± 800 kV bipolar HVDC-AC interconnected system is carried out, and both the steady state and step response performance are checked to verify the accuracy of the model. Finally electromagnetic transient of the system under different faults is investigated, including different grounding faults on AC side, fault on DC side and fault of filters. Transient responses are analyzed, including the recovering time from oscillation caused by faults and possibility of commutation failure (CF). Show more

Keywords: Electromagnetic transient, HVDC interconnected system, CF, short-circuit fault, open-circuit fault

DOI: 10.3233/JAE-131737

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 69-86, 2014

Authors: Wang, Xiuchen | Liu, Zhe | Zhou, Zhong

Article Type: Research Article

Abstract: Blended electromagnetic interference (EMI) shielding fabric has an important application in the EMI shielding fields, but its shielding effectiveness (SE) computation remained unsolved. This study proposes a fast computation method which builds a virtual metal model according to fabric structure parameters to calculate the SE of the EMI shielding fabric. The above analysis involves the calculation of metal fiber content per unit volume of the EMI shielding fabric according to the structure of the fabric, followed …by construction of a virtual metal model and computation of its thickness. Then a relation between the SE of the EMI shielding fabric and the SE of the virtual metal model is explored. A conversion coefficient of the SE computation of plain, twill and satin weave fabric is determined by experiments. A fast computation of the SE based on the virtual metal model is built. After a number of experiments, results show that the relative error is low and the computation is fast and is satisfied for the normal blended EMI shielding fabrics. Show more

Keywords: Shielding effectiveness, fast computation, blended electromagnetic interference shielding fabric, virtual metal model

DOI: 10.3233/JAE-131738

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 87-97, 2014

Authors: Cheng, Qiang | Zhang, Zhendong | Guo, Hui | Xie, Nailiu

Article Type: Research Article

Abstract: A new near-net-shape technology (MIM Technology) has been first introduced to GDI injector processing expected to solve the problems of inefficiency, low machining accuracy, low material utilization rate and unstable performance that exist in traditional processes. In order to improve the comprehensive performance of GDI injector Fe-based Nano-crystalline, soft magnetic alloy material has been used, and some structures of the magnetic circuit parts have been optimized. The excellent machinability, physicochemical properties, materials …applicable of the MIM technology has been analyzed by tracking test. The comprehensive performances of different GDI injector samples have been analyzed by simulation analysis and experimental validation. As a result, the samples which were processed by the MIM technology reduce the skin effect and eddy current loss by 9.8%, accelerate the starting current rise rate by 2.5% and shorten the dynamic response time by 14.2%. The dynamic injection quantity increases by about 2.5%, and the linear range of dynamic fuel injection quantity is expanded about 9.6%. Show more

Keywords: MIM technology, GDI injector, electromagnetic finite element, dynamics response, dynamic fuel injection quantity

DOI: 10.3233/JAE-131739

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 99-114, 2014

Authors: Liu, Zehui | He, Wei | Yang, Fan | Zhai, Jinqian | Zhang, Ruiqiang

Article Type: Research Article

Abstract: In the MLPG method of this paper, only the boundary integrations over local subdomains is involved, which make the MLPG method is very easy to carry out because the local sub-domains are chosen in MLPG method as simple circular or rectangular ranges. In order to simplify the MLPG method, the radius of local sub-domains has been adjusted for the nodes close to the global boundary but not exactly on the boundary. In addition, the boundary conditions …including the essential and natural boundary are imposed directly by the nodes which are exactly on the global boundary. Two electromagnetic models have been studied in this paper to investigate the accuracy and computational efficiency of the MLPG method. The results, which are compared with the solutions obtained from the MLPG in the reference and the FEM, show that the MLPG method in this paper can obtain more accurate results by using fewer nodes. Show more

Keywords: Local Petrov-Galerkin method, meshless, electromagnetic problems

DOI: 10.3233/JAE-131740

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 1, pp. 115-123, 2014