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1.
This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time‐consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct‐current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 7–15, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20310 相似文献
2.
Recently, a demand for small-capacity generators has been increasing as electric sources in small ships and automobiles or as portable electric sources driven by engines. It is desired that the structure of small-capacity generators be simple and robust, and that the generators be highly reliable, easily maintained and controlled. This paper describes an analysis of the original brushless synchronous generator without exciter. The output voltage can be adjusted in the wide range by controlling the stator dc current. To analyze the characteristics of this generator, the finite element method is applied. It is found that the results of theoretical analysis agree well with the experimental results. 相似文献
3.
Motoharu Fujigaki In Hong Yang Yoshiharu Morimoto Eung Kyo Han 《NDT & E International》1996,29(4):197-203
There is no good method to measure the shape and the strain distributions of a structure changing with time. We have previously proposed the Fourier transform grid method (FTGM) to measure the three-dimensional shape and surface strain distributions of stationary objects by analysing the two-dimensional grating images recorded with two cameras. In the stereoscopic method, it is very important to determine the accurate geometric parameters of the camera system. In this paper, the positions and the directions of cameras are accurately determined using the FTGM applied to images of a reference object on which a two-dimensional grating is drawn. Applications for analysing shape and strain distributions of vibrating rubber plates and a moving human skin are shown. 相似文献
4.
金永杰 《核电子学与探测技术》1989,9(1):10-17
本文所提出的投影域重建——再投影迭代算法可以恢复不完整的扇形束投影数据,从而实现从有限的投影数据重建图象。这种算法把滤波——反投影图象重建过程和再投影的过程纳入一个公式,仅在投影域上估算未知的投影数据,因此避免了重建过程和反投影过程中的插值运算,改善了收敛性,提高了计算精度,缩短了运算时间。模拟实验表明:即使有70%的投影数据丢失,经过两次迭代就能以令人满意的精度恢复丢失的投影数据。 相似文献
5.
Kotaro Matsuuchi Tadashi Fukami Nobuyuki Naoe Ryoichi Hanaoka Shinzo Takata Toshio Miyamoto 《Electrical Engineering in Japan》2005,150(2):43-49
This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033 相似文献
6.
Monitoring of nitrate (NO3-) and nitrite (NO2-) content in agricultural products in Slovenia has been carried out since 1996. The results of monitoring over the period 1996-2002 are presented. During this time 924 samples of 14 different agricultural products (potato, lettuce, apples, carrot, silage maize, cabbage, grapes, peaches, string beans, cereals, pears, cucumbers, strawberries and tomato) were analysed. The samples were taken at the time of maturity directly from growing sites and they were analysed using segmented flow analysis. The average nitrate contents were the highest in lettuce (1074 mg kg-1), cabbage (881 mg kg-1), string beans (298 mg kg-1) and carrot (264 mg kg-1), and they were moderately high in potato (158 mg kg-1), silage maize (122 mg kg-1), strawberries (94 mg kg-1), cucumbers (93 mg kg-1) and cereals (49 mg kg-1). Low nitrate contents (below 6 mg kg-1) were found in fruit (grapes, peaches, apples and pears) and tomato. With the exception of cereals (8.9 mg kg-1), apples (1.5 mg kg-1), potato (1.2 mg kg-1) and pears (1.0 mg kg-1) the content of nitrites did not exceed 0.5 mg kg-1. It may be concluded that the results of the monitoring were in most cases similar to the results of investigations obtained in other countries. 相似文献
7.
M. Nishida T. Hanabusa Y. Ikeuchi N. Minakawa 《Materialwissenschaft und Werkstofftechnik》2003,34(1):49-55
Stress measurement methods using neutron and X‐ray diffraction were examined by comparing the surface stresses with internal stresses in the continuous tungsten‐fiber reinforced copper‐matrix composite. Surface stresses were measured by X‐ray stress measurement with the sin2ψ method. Furthermore, the sin2ψ method and the most common triaxal measurement method using Hooke's equation were employed for internal stress measurement by neutron diffraction. On the other hand, microstress distributions developed by the difference in the thermal expansion coefficients between these two phases were calculated by FEM. The weighted average strains and stresses were compared with the experimental results. The FEM results agreed with the experimental results qualitatively and confirmed the importance of the triaxial stress analysis in the neutron stress measurement. 相似文献
8.
S. H. Ahmad 《Polymer International》1992,28(4):291-294
Measurement of the flow stress of high density polyethylene (HDPE) and nylon 66 at strain rates of 103 s?1 using a split Hopkinson pressure bar technique is discussed. The flow stress at a strain of 10% has been determined for both polymers at 20°C. The intrinsic errors involved in this technique are briefly reviewed. The results indicate that the flow stress of HDPE and nylon 66 were 50MPa and 150MPa, respectively, at strain rates of about 103s?1. 相似文献
9.
CHEN KeFan DENG JianHua ZHAO Fei CHENG GuoAn &ZHENG RuiTing Key Laboratory of Beam Technology Material Modification of Ministry of Education College of Nuclear Science Technology Beijing Normal University Beijing China 《中国科学:信息科学(英文版)》2010,(3)
The structures and field emission properties of multi-walled carbon nanotube arrays implanted with Zn+ by MEVVA ion implanter have been investigated.The results revealed that Zn+implantation induced structural damage and that the top of carbon nanotubes with multi-layered graphite structure were transformed into carbon nanowires with amorphous structure.Meanwhile,C:Zn solid solution was synthesized after Zn+ implantation.The turn-on field and threshold field were 0.80 and 1.31 V/μm,respectively for original... 相似文献
10.