Gakuen cho

Sakai, Japan

Gakuen cho

Sakai, Japan
SEARCH FILTERS
Time filter
Source Type

Yanagimoto H.,Gakuen cho
Artificial Life and Robotics | Year: 2017

In this paper, a new access log analysis is proposed which estimates both active states and inactive states from observations simultaneously. I improved burst analysis and developed enthusiasm analysis to detect not only active states but also inactive states. Speaking concretely, I constructed a generative model that assumed observations, which meant event occurrence frequency in this paper, were generated under some Poisson distributions. The generative model based on Poisson distributions consists of some distributions including (Formula presented.)s which are less than average frequency and more than average frequency. A cost function, which consists of log likelihood and state transition cost, is defined and enthusiasm levels are estimated from the observations minimizing the cost function. The proposed method was applied to query occurrence data in access logs and I confirmed the proposed method could find active states and inactive states from submission patterns and the results showed relationship between enthusiasm levels and real events. © 2017 ISAROB


Katahira T.,Kagamiyama | Naka T.,Yuge Shimoyuge | Kohzu M.,Gakuen cho | Yoshida F.,Kagamiyama
Key Engineering Materials | Year: 2013

In the present work, FLDs of AZ31 magnesium alloy sheet for non-proportional strain paths were investigated by performing two-step stretch forming experiments at various forming speeds (3, 30 and 300 mm.min -1) at elevated temperatures of 150, 200 and 250°C. The forming limit strains, both for proportional and non-proportional deformations, increased with temperature rise and with decreasing forming speed. A FLC after a uniaxial pre-strain lies outside of the proportional FLC for a given condition of temperature and forming speed, whereas a biaxially pre-strained FLC lies inside of the proportional FLC. It was found that the accumulated effective plastic strain and the direction of plastic strain increment at the final stage of forming are two major factors that influence the forming limits for non-proportional deformations. © (2013) Trans Tech Publications, Switzerland.


Katahira T.,Kagamiyama | Hosokawa S.,Kagamiyama | Naka T.,Yuge Shimoyuge | Kohzu M.,Gakuen cho | And 2 more authors.
Advanced Materials Research | Year: 2014

Magnesium alloy sheets have a potential to be widely used in many fields of industry due to their excellent lightweight property. Although magnesium alloys have low ductility at the room temperature due to their hexagonal close-packed structure, their formability can be improved at elevated temperatures. Therefore, warm press-forming of magnesium alloy sheets is an attractive technology. The objective of the present work is to investigate the cyclic plasticity behavior of an AZ31 sheet at elevated temperatures by performing cyclic tension-compression experiments. The cyclic deformation mechanism is examined by measuring the crystallographic orientation distributions by means of X-ray diffraction method at each stage of the cyclic deformation. The present findings are summarized as follows: (1) Stress-strain responses of an AZ31 sheet were investigated at various temperatures (R.T, 100, 150 and 200°C) at strain rates of 0.001, 0.01 and 0.05 s-1. The flow stresses were insensitive to the strain rate at the room temperature, however the strain rate dependency of the flow stress becomes dominant at elevated temperatures of over 100 °C. (2) Cyclic plasticity behavior of the sheet at various elevated temperatures (R.T, 100, 150 and 200°C) at strain rates of 0.001, 0.01 and 0.05 s-1 were investigated by performing warm in-plane cyclic compression-tension test. Similarly to the uniaxial tension test, apparent temperature and strain rate dependencies of the flow stress were observed at temperatures of over 100 °C. (3) At the room temperature an unusual cyclic stress-strain curve, which is very different from that of bcc and fcc metals, was observed. From the texture measurement it was found that such a specific stress-strain characteristic is due to its twinning and detwinning deformation mechanism. (4) In contrast, at an elevated temperature of 200°C, the usual cyclic stress-strain response, which is similar to one appearing in most of metallic materials, was observed. This is because the major deformation mechanism at an elevated temperature is the slip, rather than twinning/detwinning, since the CRSS decreases drastically with increasing temperature. © (2014) Trans Tech Publications, Switzerland.

Loading Gakuen cho collaborators
Loading Gakuen cho collaborators