Kihachiro Tanaka

Magnetic resonance imaging apparatus having vibration damping means on gradient coil

A magnetic resonance imaging apparatus includes a magnet for generating a static magnetic field, a gradient coil for generating a gradient magnetic field in a measurement space, and a vibration damping means which includes a container and granular material disposed in the container. The vibration damping means is installed with a supporting bolt between the gradient coil and a supporting means. Since the gradient coil is supported at a constant position without any vibration and deformation, the magnetic resonance imaging apparatus generates an accurate image signal without any acoustic noise.

Measurements of transient motion of magnetic disk slider

To study slider flying characteristics for the magnetic disk unit, a new measuring system for determining slider flying height, i.e. spacing, is developed. Experimental results of slider motion were measured statically and dynamically, then compared with theoretical results, and examined.

Control of human generating force by use of acoustic information

We have performed basic experiments for the purpose of applying onomatopoeia to engineering problems. In these experiments, test subjects were made to perform lifting actions while listening to onomatopoeic utterances. We thereby demonstrated that there is a relationship between the onomatopoeic utterances and the lifting forces exerted by the test subjects. We examined how the lifting forces are related to the envelope of onomatopoeic utterances. Furthermore, we investigated how the lifting force is affected depending on whether or not emotion is expressed when uttering the onomatopoeia.

Estimation of the variance of steady vibration responses of structures with random parameters and method to compute the allowable variance of the parameters

Abstract When parameters contributed to mass and rigidity of the structures have randomness, the steady vibration responses of the structures have random characteristics. In this paper the method to estimate the variance of the response and to compute the allowable variance are described. In the computation the partial derivative method is used and effectiveness of the method is examined for simple numerical examples.

Dynamics of Lure Casting (Influence of Lure Weight)

Fly-fishing and lure fishing have been positioned as sports deliberately different from the traditional Japanese fishing-style. In the case of lure fishing, casting is the element which anglers must master in order to cast a lure at an appropriate position. Lure fishing constitutes various elements, for example, casting, reeling, hooking and landing, but the importance that casting holds is extremely large. This study uses experimental and computational analyses to investigate the dynamic behavior of lure casting. The casting process and the timing of the lure released are important for the proper presentation of lure. Moreover, the shape of a rod before the lure released is important for a long cast or controlled cast. However, it is difficult to grasp the phenomenon or to make a numerical model. Therefore, the most suitable casting method will be clarified from the viewpoint of sports engineering and human dynamics. In this paper, the system of rod and lure is modeled, and the behavior of the rod and the flying distance of a lure are calculated. Especially, influence of lure weight is clarified.

A Study on Passive-Adaptive Vibration Control Elements Using Dilatant Materials.

Adaptive vibration control is a method that changes vibration system characteristics according to the vibration level. To construct adaptive vibration control elements that do not require any external energy, called passive adaptive vibration control elements, we have proposed a method that uses nonlinear viscoelastic materials. This paper describes how we constructed these elements using dilatant materials and reports on the experiments we conducted with them. The results show that the vibration of mass supported by these elements is reduced when the vibration level is high. They also show that vibration is isolated by these elements when the vibration level is low.

Influence of Printhead Vibration in Impact Printer on Printing Quality

In order to obtain good printing quality with impact printers, a method of reducing vibration by carriage mounting printheads is investigated using a newly developed simulator for vibration analysis and experimental tests. As a result of a survey of various parameters, optimizing the carriage driving control pattern and increasing the stepper motor damping proved to be effective for decreasing carriage vibration. Consequently, significant improvement in printing quti1ity is obtained.