Yutaka Shoukaku

Oscillations of nonlinear hyperbolic equations with functional arguments via Riccati method

This paper is devoted to the study of the oscillatory behavior of solutions of nonlinear hyperbolic equations with functional arguments by using integral averaging method and a generalized Riccati technique. First, we establish oscillation results for nonlinear hyperbolic equations by applying oscillation criteria for Riccati inequality. Secondly, we present interval oscillation results for nonlinear hyperbolic equations. These results improve and extend oscillation results of Cui and Xu [1].

Forced oscillation of certain neutral hyperbolic equations with continuous distributed deviating arguments

In this paper, we consider certain hyperbolic equations with continuous distributed deviating arguments, and sufficient conditions are presented for every solution of some boundary value problems to be oscillatory in a cylindrical domain. Our approach is to reduce multi-dimensional problems to one-dimensional problems by using some integral means of solutions.

Forced oscillatory result of hyperbolic equations with continuous distributed deviating arguments

Abstract In this paper, we consider hyperbolic equations with continuous distributed deviating arguments, and sufficient conditions are presented for every solution of some boundary value problems to be oscillatory in a cylindrical domain. Our approach is to reduce multi-dimensional problems to one-dimensional problems by using some integral means of solution.

Forced Oscillation Criteria for Nonlinear Hyperbolic Equations via Riccati Method

In this paper, we consider the nonlinear hyperbolic equations with forcing term. Some su-cient conditions for the oscillation are derived by using integral averaging method and a generalized Riccati technique. We shall provide oscillation results of solution of the hyperbolic equation (E) @ @t µ r(t) @ @t u(x;t) ¶ + p(t) @ @t u(x;t) ia(t)¢u(x;t) i k X i=1 bi(t)¢u(x;?i(t))

Friction and Wear Properties of PTFE Composites Against 6061-T6 Aluminum Alloy Under Hydrogen Atmosphere

The friction and wear properties of polymer were investigated under a hydrogen atmosphere, by using PTFE (polytetrafluoroethylene) and two kinds of PTFE composites. Experiments were also conducted in air, nitrogen, and vacuum environment. The experiment carried out by pin-on-disk friction and wears apparatus in the vacuum chamber. Pin specimens are no filling PTFE, Gr-filled PTFE (Gr filled with 25 wt%) and MoS2 –filled PTFE (MoS2 filled with 25 wt%). Friction disk is aluminum alloy 6061-T6 with 0.02μm surface roughness. Aluminum alloy 6061-T6 is able to use for apparatus for hydrogen. After experiments, specific wear rate was calculated, specimen surface, wear track and wear debris were observed, surface profile of the wear track were measured. The specific wear rate of unfilled PTFE and PTFE/MoS2 of in air was lower than the other atmospheres. The A6061-T6 disk was worn by PTFE pin specimens and in the case of wear track was much rougher, the specific wear rate of pin specimens tended to increase without unfilled PTFE in air and PTFE/Gr.Copyright

Measurement of Pressure Distribution of Shoe Sole During Walking and its Relation to Slippage

Every year, many people are injured by slipping and falling accidents when walking. Clarification of the mechanism of slipping and falling may provide insight into possible solutions. The purpose of this study was to reveal the behavior of the shoe sole contact during walking by measuring both contact pressure distribution and the slippage of shoe sole blocks. A force plate with a walkway made of glass was produced to observe the contact area between the walkway and the shoe sole. The total internal reflection of light was used to distinguish the contact area and noncontact area of the shoe sole. The slippage of the shoe sole was measured by time-sequence position variations of each block. As a result, a large traction coefficient and a large slippage of the shoe sole block were found to occur immediately after the heel strike. Slippage was also detected at the period of toe off. Moreover, the maximum contact pressure of each block varied from 1.0MPa to 3.0MPa in the contact area.Copyright