Time filter

Source Type

Gamagori, Japan

Aichi University of Technology is a private university in Gamagōri, Aichi, Japan. The school opened as a junior college in 1987. It became a four-year in 2000. Wikipedia.

Large numbers of studies have focused onmicrorobots and numerous contests are held annually to develop microrobot technologies. These activities have resulted in that various types of microrobots have been proposed. They include motor, piezoelectric-element, and electromagnet microrobots. We consider a mechanism of movement and a method of control for an electro-magnet microrobot that both runs in a straight line and turns using a single electromagnet coil by adjusting the direction of the robot's permanentmagnets and the input voltage applied to the electromagnet coil. The microrobot's straight running forward is modeled mathematically and its motion features are studied on horizontal and inclined planes through simulation and some experiments. In addition, turning characteristics is studied using an experiment. Source

Chen M.,Chaoyang University of Technology | Mizutani S.,Aichi University of Technology | Nakagawa T.,Aichi Institute of Technology
International Journal of Reliability, Quality and Safety Engineering | Year: 2010

This paper proposes a random and age replacement policy for an operating unit which works at random times. First, the unit is replaced before failure at a planned time T or at the completion of a working time, whichever occurs first. The expected cost rate is obtained. Next, as one extended model, the unit is replaced before failure at a number N of working times or at a planned time T. An optimal policy which minimizes the expected cost rate is discussed analytically, and its numerical example is given. Two modified models, where the unit is replaced at the first completion of the working time over time T or at number N, and it is replaced at time T or number N, whichever occurs last, are considered. Furthermore, we show that this corresponds to a cumulative damage model by replacing shock with work. Finally, one optimization problem of how much time to preset for scheduling the completion of N works is proposed. © 2010 World Scientific Publishing Company. Source

Nakagawa T.,Aichi Institute of Technology | Mizutani S.,Aichi University of Technology | Chen M.,Chaoyang University of Technology
Reliability Engineering and System Safety | Year: 2010

Some systems work for a job with random working times. It would be useful for such systems that they are checked at the completion of working times to detect their failures, which is called a random inspection policy. Two inspection policies, where a system is checked at periodic or successive times and also at every completion of working times, are considered. The total expected costs until the detection of failure are obtained, and when the random working time is exponential, optimal inspection policies which minimize them are derived analytically. Furthermore, the inspection policy where the system is checked only at every completion of N th working time is proposed. Finally, as one of modified random inspection models, the backup model where the system goes back to the latest checking time when it has failed is taken up and analyzed, by using the inspection policy. © 2010 Elsevier Ltd. All rights reserved. Source

Tamano S.,Nagoya Institute of Technology | Itoh M.,Aichi University of Technology
Journal of Turbulence | Year: 2012

The drag-reducing effect of a spanwise-traveling wave with wall deformation on a zeropressure-gradient turbulent boundary layer over a flexible sheet was investigated. The test plate placed in the wind tunnel consisted of a flexible sheet section, where the traveling wave motion was generated by a vibration device with a crank via upstream and downstream smooth rigid wall sections. Streamwise and wall-normal velocity components were measured by single and cross hot-wire anemometers. Amplitude and frequency of the spanwise-traveling-wave motion were measured using two laser displacement sensors. The drag reduction ratio was estimated from the friction coefficients through the growth rate of the momentum thickness of the turbulent boundary layer over the flexible sheet section. A maximum drag reduction ratio DR of up to 13% was obtained. The relations between sheet displacement and streamwise and wall-normal velocity fluctuations were compared at a large DR (DR = 8%) and at a very small DR (DR = 2%), which was almost the same as the no drag reduction case, taking into account the experimental uncertainty. For the larger drag reduction, a slow-velocity fluctuation with large amplitude appeared further away from the flexible sheet. Quadrant analysis of streamwise and wall-normal velocity fluctuations revealed that the drag reduction was attributed to a reduction in the sweep event and an increase in the negative contribution of the inward-interaction event to the Reynolds shear stress due to the sheet displacement fluctuation. © 2012 Taylor & Francis. Source

Tamano S.,Nagoya Institute of Technology | Itoh M.,Aichi University of Technology
Journal of Turbulence | Year: 2011

In this study, turbulence structures of drag-reducing turbulent boundary layers in surfactant solutions at the momentum-thickness Reynolds number Reθ ≃ 800 were compared at large and small drag reduction ratios DR = 78% and 34% at the solution temperature, T = 30°C and 35°C. Turbulence statistics and structures were obtained by a two-component laser-Doppler velocimetry (LDV) and particle image velocimetry (PIV) systems for the streamwise and wall-normal (x-y) plane and the streamwise and spanwise (x-z) plane. The quadrant analysis of streamwise and wall-normal velocity fluctuations revealed that at DR = 78%, the positive contribution of sweep and ejection events to the Reynolds shear stress was comparable with the negative contribution of inward-interaction and outward-interaction events, so that the Reynolds shear stress was almost zero. At DR = 34%, the maximum positive contributions of quadrants II and IV and the maximum negative contributions of quadrants I and III were comparable with those of the corresponding water near the wall, but the region of positive contributions in quadrants II and IV became narrower and the region of negative contributions in quadrants I and III became wider, so that the Reynolds shear stress decreased. At DR = 78%, in high activity, the streamwise velocity fluctuations were smaller than those of water but were relatively large even near the center of the boundary layer, in addition to the near-wall region, while in low activity, the fluctuating velocity vectors were almost parallel to the wall. At DR = 34%, the scale of sweep and ejection events was much larger than that of water and the inclination angle of vortex packets at DR = 34% was much smaller than that of water. At DR = 78%, the spanwise turbulence fluctuation was strongly suppressed and vortical structures were not observed on the (x-z) plane, while at DR = 34%, several vortical structures, which seemed to correspond to the cross section of legs of hairpin vortices, were observed near the wall. Under the assumption of frozen turbulence, it was found that for both DR = 78% and 34%, the high- and low-speed regions were aligned laterally, although the low-speed regions at DR = 78% were obscured. © 2011 Taylor & Francis. Source

Discover hidden collaborations