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An Open-Loop Method for Point-to-Point Positioning of a Piezoelectric Actuator
Henmi, Nobuhiko,Tanaka, Michihiko Korean Society for Precision Engineering 2007 International Journal of Precision Engineering and Vol.8 No.2
We describe how to control a piezoelectric actuator using the open-loop method for point-to-point positioning. Since piezoelectric actuators have nonlinear characteristics due to hysteresis and creep between the input voltage and the resulting displacement, a special method is required to eliminate this nonlinearity for an open-loop drive. We have introduced open-loop driving methods for piezoelectric actuators in the past, which required a large input voltage and an initializing motion sequence to reset the state of the actuator before each movement. In this paper, we propose a new driving method that uses the initializing state. This method also utilizes the overshoot from both the upward and downward stepwise drives. Applying this method., we obtained precise point-to-point positioning without the influence of hysteresis and creep.
An Open-Loop Method for Point-to-Point Positioning of a Piezoelectric Actuator
Nobuhiko Henmi,Michihiko Tanaka 한국정밀공학회 2007 International Journal of Precision Engineering and Vol.8 No.2
We describe how to control a piezoelectric actuator using the open-loop method for point-to-point positioning. Since piezoelectric actuators have nonlinear characteristics due to hysteresis and creep between the input voltage and the resulting displacement, a special method is required to eliminate this nonlinearity for an open-loop drive. We have introduced open-loop driving methods for piezoelectric actuators in the past, which required a large input voltage and an initializing motion sequence to reset the state of the actuator before each movement. In this paper, we propose a new driving method that uses the initializing state. This method also utilizes the overshoot from both the upward and downward stepwise drives. Applying this method, we obtained precise point-to-point positioning without the influence of hysteresis and creep.
Nobuhiko Henmi,Yuta Sumi,Michihiko Tanaka 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.1
A displacement magnification mechanism which uses flexure motion guide using elastic hinges can realize smooth frictionless motion but has poor vibration damping capability. An impact damper is a damping mechanism which uses collision energy to dissipate vibration energy. If the damper is used for vibration control of the flexure mechanism, it may be able to dissipate unexpected vibration without killing the merits of the flexure mechanism. In the paper, a loading type impact damper is applied to settle down transient vibration of a displacement magnification mechanism. We investigate differences of damping effect by setting conditions of the damper. It is shown that the impact damper can eliminate residual vibration at step response effectively without steady state error. The experimental displacement magnification mechanism with impact damper can settle down less than 1/5 of the response without the damper under appropriate setting conditions. Influence of natural frequency ratio between damper and displacement magnification mechanism is investigated. Influences of indentation at impact point are also examined.
Nukaga, Masako,Henmi, Sakae The Korean Ceramic Society 2000 The Korean journal of ceramics Vol.6 No.3
The generation of the intermodulation noises in microwave isolators has been studied in relation to the characteristics of YIG ferrites designed for this application. We have investigated the influences of porosity and crystalline anisotropy related to the magnetic loss, which causes the generation of intermodulation signals. The power dependence of the intermodulation power level is stressed as the crystalline anisotropy decreases. These results are consistent with the nonlinear effects of a single normal mode before the excitation of the spin-waves. It also appears that this power level is proportional to the magnitude of dc bias magnetic field.
Rotating Choke and Choked Surge in an Axial Pump Impeller
Watanabe, Toshifumi,Sato, Hideyoshi,Henmi, Yasuhiko,Horiguchi, Hironori,Kawata, Yutaka,Tsujimoto, Yoshinobu Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.3
Unlike usual turbopump inducers, the axial flow pump tested operates very stably at design flow rate without rotating cavitation nor cavitation surge. Flow visualization suggests that this is because the tip cavity smoothly extends into the flow passage without the interaction with the leading edge of the next blade. However, at low flow rate and low cavitation number, choked surge and rotating choke were observed. Their correlation with the performance curve under cavitation is discussed and their instantaneous flow fields are shown.
Lee, Deog Bae,Lee, Kyung Bo,Henmi, Teruo,Kim, Jae Duk 한국환경농학회 2000 한국환경농학회지 Vol.19 No.5
1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including SiO₂ and Al₂O₃ derived from inorganic compounds remained after burning. As minor components, Fe₂O₃ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and Fe^(3+)) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 cmol^+·㎏^(-1) and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(lg) could remove 123.5 ㎎ of zinc, 164.7 ㎎ copper, 184.4 ㎎ cadmium and 350.6 ㎎ lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 ㎏·ha^(-1) to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased 1.1∼3.2 times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by 27∼75%. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 cmol^+·㎏^(-1). AGZ had Na-Pl peaks mainly with some minor C₃S peaks in X-ray difftactogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of NH₄^+ and negatively with that of PO₄^(3-). Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 ㎏) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.