Applied Electromagnetic Engineering for Advanced Materials from Macro-to Nanoscale under Static-to Shock Loading

Paper Title Page

Authors: Masato Enokizono
Abstract: This paper describes the technical problems for upgrading efficiency by core loss reduction on high speed motor. These contents are based on the ultra-thin electrical steel sheet for motor core and vector magnetic characteristic technology. It is difficult to get successful results by replace of high performance core materials. Because the utilization technique of these materials is necessary as recipe for research and development of high efficiency high speed motor.
Authors: Mohachiro Oka, Masato Enokizono, Yuji Mori, Kazumasa Yamazaki
Abstract: We are developing a low-loss stator core for high-speed and small-size motors using an ultrathin electrical steel sheet. This stator core for a high-speed motor was produced using a 0.08mm-thick ultrathin electrical steel sheet. Additionally, in order to evaluate the iron loss of the high-speed motor stator core, we constructed a high-speed building factor evaluation system. This evaluation system is composed of high-speed A/D converters, a D/A converter, and a high-speed power amplifier. The B-H curve and the iron loss of the high-speed motor stator core (0.08mm_Core), which was made of the 0.08mm-thick ultrathin electrical steel sheet, were measured using the outer excitation method and the high-speed building factor evaluation system. The iron loss of the 0.08mm_Core was about 66% of the iron loss of the ordinary-speed motor stator core (the 0.35mm_Core) which was made of a 0.35mm-thick electrical steel sheet. Each iron loss in two kinds of cores was measured using the outer excitation method at the excitation frequency (fex) 1000Hz and the maximum excitation magnetic flux density (Bexmax) 1.0T. From experimental results, the iron loss of the 0.08mm_Core in the high frequency excitation was very small.
Authors: Mehmet Kuru, Erhan Ongun, Asım Özmeti̇n, Mehmet Hançer, Ali Esad Özmeti̇n
Abstract: Fabrication of hard magnetic thin films is a key issue on the development of new micro electro mechanical systems. As the magnetically hard SmCo thin-films offer excellent intrinsic magnetic properties, such as moderate saturation magnetization, large magnetic anisotropy, and high Curie temperature, they are considered as a promising candidate to be used for novel MEMS applications. In this work, SmCo5 thin films with Cu underlayer were grown onto Si (100) substrate at room temperature by RF magnetron sputtering technique. The samples were annealed at 400 ̊C and 500 ̊C under Ar atmosphere condition. Microstructural and magnetic properties of sputtered SmCo5 thin films were investigated by a number of advanced characterization tools and techniques. Phase composition of SmCo5 thin films was analyzed by grazing incident X-ray diffraction (GIXRD) with Cu-Kα radiation. Surface morphology was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Magnetic force microscopy (MFM) technique was used to take stray-field images of SmCo5 thin films, and finally magnetic properties were investigated to explain the coercivity of SmCo5 thin films using superconducting quantum interference device (SQUID) as a magnetometer.
Authors: Seiichi Sudo, Hiroki Kuwano
Abstract: The interfacial dynamics of a water droplet subjected to SAW (surface acoustic wave) was investigated using a high-speed video camera analysis system. The SAW device was fabricated to generate high frequency vibration for the droplet excitation. The water droplet showed bursting into a fine spray of smaller droplets and ultra-fine mist at the higher applied voltage to the SAW device. The appearance of droplet interface varied with elapsed time of surface acoustic wave excitation. At the initial stage after SAW excitation, capillary surface waves were observed on the droplet interface. Subsequently, surface disintegration due to fine spray and mist ejection was observed. The details of surface response of water droplet on the SAW device were revealed experimentally.
Authors: Aytac Onur, Mustafa Turkmen
Abstract: In this study, a novel perfect absorber (PA) array based on H-shaped nanoapertures for bio-sensing applications in infrared regime is presented. Proposed PA array has a dual-band spectral response, and the locations of these resonances can be adjusted by varying the geometrical dimensions and layer thicknesses of the structure. Nearly unity absorbance is obtained from the PA array for both resonances. The structure design is based on the near field plasmon coupling between the gold film layer and the top nanoaperture array. In this context, the dielectric spacer layer is used to support this plasmon coupling and the gold film on the silicon substrate is also utilized to eliminate the transmittance through the structure. Different dielectric spacers (MgF2, SiO2, and Al2O3) are used to investigate the effects of dielectric spacer on the absorbance characteristics of proposed PA array. High field enhancement is achieved by the interaction of the sharp corners of nanoapertures. The near field enhancements are more than 1500 times at the first resonance frequency, more than 1000 times at the second resonance frequency which is highly desirable for the infrared bio-sensing applications. Due to the high near-field enhancement and nearly unity absorbance, the proposed dual-band PA array with adjustable spectral responses can be useful for bio-sensing applications in infrared regime.
Authors: Berna Akgenc, Çetin Tasseven, Tahir Çağın
Abstract: ABO3 perovskite ceramics due to their chemical nature and size difference of the cations A (where A is a divalent metal) and B (where B is a tetravalent metal) have non-centro-symmetric polymorphs and display significant piezoelectric properties. One path to improve piezoelectric properties is through alloying these materials. In order to assess the feasibility of this, we have investigated the structure, elastic and piezoelectric properties of prototypical cubic and tetragonal phases of ABO3 bulk ceramic oxides and their alloys: {AxA`(1-x)}BO3 and A{BxB`(1-x)}O3 by density functional theory based first-principle calculations. Using 2x2x2 super cells as models in our calculations, we have covered the full alloying range by varying concentration, x, in steps of 12.5%. We have created models using Ba, Sr, Pb, for A and A`, and Ti, Zr for B and B` both in cubic and tetragonal super cells. Here, we will report the structural and piezoelectric properties of tetragonal phases of ABO3 bulk ceramic oxides and their alloys.
Authors: Tatsuo Sawada, Takuma Endo, Yuzo Shimizu, Hitoshi Nishida
Abstract: In this study, we report the theoretical resistance force of a magneto-rheological (MR) shock absorber. We use the Bingham plastic model to theoretically represent the dynamic behavior of MR fluid flow in a circular pipe under the effect of a magnetic field. Because an MR fluid has yield stresses, the flow is divided into two regions: shear flow and plug flow. We reveal the relation between the resistance force of the MR shock absorber and the applied magnetic field. We conduct experiments and compare the experimental and analytical results to verify the theoretical approach.
Authors: Yohji Okada, Ryou Kondo, Masatsugu Otsuki, Masato Enokizono
Abstract: Generally, commercial motors are produced as the lineup of series of outer diameter. The output power is changed with their length. However, the production number of space motor or power assist leg motor is small, while the power ratio versus motor weight is very important factor. The geometric study is proposed in this paper; especially, such problems of outer rotor versus inner rotor motor, outer diameter versus length. The motor characteristics are assumed with the FEM simulation. These constants depend on the motor pole number and driving amplifiers. Hence the exact geometrical dimensions should be determined with the careful simulation. Before simulation rough geometrical size can be determined, then the exact simulation will be carried out to determine the motor dimension and estimate the produced motor characteristics. The results are planned to compare with some of the experimental results.
Authors: Lidia Chubraeva, Eugeniy Evseev, Sergey Timofeev
Abstract: The first HTSC alternators developed and tested mainly contained the bulks on the rotor. The presentation covers the problem of HTSC bulks magnetizing control in an assembled cryogenic alternator with axial flux. Cylindrical bulks are positioned on the rotor of a synchronous machine and form a multi-pole excitation system. The trapped magnetic field may vary under a number of processes, magnetic flux creep included. A special system to control the value of bulk magnetization and the temperature in the cryogenic zone is developed. Similar system may by applied in cryogenic disc-type alternators with permanent magnets on the rotor.

Showing 1 to 10 of 42 Paper Titles