Motoyoshi Ohaba

Dynamic behavior of magnetic liquid drop on a solid base subject to magnetic field and vertical vibration

Abstract The surface responses of a single magnetic fluid droplet on a horizontal solid nonmagnetic base subject to magnetic field and vertical vibration have been investigated. It was found that the magnetic liquid droplet responds to the excitation in elongation and contraction. Non-linear responses were also observed at higher excitation levels.

Water distribution measurement in soil using sound vibration

Now in agriculture, it tends to save the agricultural water as much as possible. Therefore, the irrigation method using the minus pressure difference of soil water attracts attention. This method has the nature keeping the water content inside the ground. In other words, when there are crops, it is the mechanism which supplies the water content which is same quantity with the water content that it absorbed. However, effective saving water is not able to be performed, because the water distribution in soil is difficult to grasp. Therefore, we propose a method of monitoring and imaging of the water content in the rooting zone using a sound vibration and the scanning laser Doppler vibrometer (SLDV). The plastic container (40×50×30 cm) which is made from acrylic in the laboratory that had been filled with sand of uniform particle size (200 to 300 μm) was used for this experiment. In this experiment, it measures the status of the water distribution by the change of the vibration propagation. The making method ...

Liquid surface behavior of a magnetic liquid in a container subjected to magnetic field and vertical vibration

Abstract The surface responses of a magnetic fluid in a container subject to a magnetic field and vertical vibration are examined. Three kinds of observations were made in these experiments: mapping stability boundaries, determining nonlinear surface responses, and a comparison between cases with and without magnetic fields.

Proton Nuclear Magnetic Resonance and Optical Microscopic Studies of Magnetic Fluids

Proton nuclear magnetic resonance has been studied for 1 H in the solvent of super-paramagnetic fluid in which fine particles of magnetite, Fe 3 O 4 , are suspended as colloid. An optical microscope has been used to observe the filamentary agglomeration of colloidal clusters under an applied magnetic field, H 0 . The filaments are aligned in the direction parallel to H 0 within a minute after the application of the magnetic field of 1 kOe. An average of local magnetic fields at the positions of 1 H is antiparallel to the direction of H 0 , and its magnitude depends on the arrangements of filaments. A tentative estimate of the interacting force between a colloidal cluster and a filament has been done by the measurement of the growing velocity of filaments. The force is estimated to be an order of 10 -19 dyne (10 -24 N) under H 0 of 1.1 kOe.

Dynamic characteristics of a magnetic fluid column formed by magnetic field

Abstract This paper examines the dynamic characteristics of liquid columns when lateral sinusoidal vibration is applied. The first, second and third resonant frequencies shift to a higher frequency region as the magnetic field intensity increases. For a magnetic fluid column, the second and third resonant frequencies show interesting behaviour as the magnetic field is varied.

Oscillations of magnetic liquid columns subject to random vibration

Abstract The interfacial impulse response of the axisymmetric mode (0,1) of a finite liquid column in a microgravity environment is simulated using magnetic liquids and random vibration.

Nonlinear shape oscillations of axisymmetric magnetic fluid columns in a magnetic field

Nonlinear axisymmetric shape oscillations have been revealed through experiments conducted with large-amplitude forced vertical vibrations of a magnetic fluid column supported by a magnetic field in the presence of gravity. Those nonlinear shape oscillations are characterized by the jumping phenomena, mode transition, and subharmonic motions.

Behavior of Magnetic Liquid Drop on a Solid Base Subject to Vertical Vibration.

The dynamic behavior of a magnetic liquid drop on a non-magnetic solid base subject to magnetic fields and vertical vibration have been studied experimentally and theoretically. The frequency responses of a single magnetic liquid droplet are investigated. Measurements have been made of the amplitude of time-varying height and the contact angle of a magnetic droplet on a horizontal solid base. It was found that the magnetic liquid droplet responds to the excitation in the elongation and contraction of its height. The frequency of the time-varying droplet height and contact angle corresponded to the excitation frequency. Theoretical analysis explains the experimental results of the droplet motion, that is, the droplet height is determined by the Bond number, the magnetic Bond number and the vibration Bond number.