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Reversal of Travel Time between ”Zipper” and ”Non-Zipper” Mergingin Traffic Flow
Ryosuke Nishi,Hiroshi Miki,Akiyasu Tomoeda,Katsuhiro Nishinari 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
Heavy traffic congestion occurs daily at an intersection of high way traffic. For releasing this congestion, the effect of ”zipper” merging of vehicles is discussed in this paper. This is the merging of vehicles on two lanes alternatively, and is achieved only by the local communication of vehicles between two lanes before merging. This ”zipper” merging is compared with the ”non-zipper” merging, which is the merging without interactions of vehicles before merging, interms of travel time. This investigation is performed by using numerical simulations with a new multiple-lane cellular automaton model which has slow-to-start effect. Numerical results show that the reversal of travel time between ”zipper”, and ”non-zipper” merging is observed as the change of slow-to-start effect.
Analysison Pedestrian Out flow through an Exit with an Obstacle
Daichi Yanagisawa,Ayako Kimura,Akiyasu Tomoeda,Ryosuke Nishi,Yushi Suma,Kazumichi Ohtsuka,Katsuhiro Nishinari 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
We have found that putting an obstacle in front of an exitin creases the pedestrian out flow through an exitinane vacuation situation from our experimets. In this paper, conflicts and turning, which affects the pedestrian out-flow significantly, is studied in detail to analyze the effect of an obstacle. In the floor field model, which is apedestri and ynamics modelu sing cellularauto mata, conflicts are taken in to account by the frictional parameter, which is not suffi-ciently realistic, and turning is neglected. Therefore, we have improved the frictional parameter to the frictional function, which is more realistic than the frictional parameter, and introduced the turning function, which represents the decrease in walking speeds when pedestrians turn. The frictional and the turning function clearly explain the mechanism of the effect of the obstacle, i.e., the obstacle blocks apedestrian moving to the exitand decreases the average number of pedestrians involved in the conflict.
Bending fatigue strength of case-carburized helical gears (In the case of large helix angles)
Kengo Nojima,Kengo Ogata,Motomu Tanaka,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12
Case-carburizing enlarges the depth of the hardened layer at the tooth width end on the acute angle side of helical gears. For the helical gears with large helix angles (Exceeding 25°), this hardened layer may lower their bending fatigue strength. Therefore, we investigated the influence of this hardened layer on their bending fatigue strength through the bending fatigue tests. Our results suggest that this hardened layer might reduce the case-carburizing’s effect to enhance their bending fatigue strength. Thus, using only the maximum tooth root stress would be inadequate for evaluating their bending fatigue strength, and it would be necessary to consider the relationship between the hardened layer and the tooth root stress distribution (Especially, the stress applied at the tooth width end on the acute angle side) from the beginning of meshing to the end.
Tomoaki Ikuta,Kazuyoshi Takahama,Kengo Nojima,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12
Discarding case-carburized gears with excessive case-depth causes financial and environmental losses. To save the losses, we experimentally investigated the applicability of case-depth modification by additional heat treatments (AHTs) to such gears in terms of bending fatigue and impact strength. The AHTs consisted of an intermediate softening treatment (IST) (vacuum normalizing, tempering, induction normalizing, or none) to case-carburized spur gears with an excessive case-depth, followed by induction heating and quenching. All the AHTs reduced the effective case-depth, maintained the surface residual stress, refined the microstructure near tooth root surfaces, and maintained the bending fatigue limit. Moreover, all the AHTs increased the impact limit because of the refinement of the microstructure, whereas omitting an IST reduced this increase. Thus, case-depth modification by AHTs is applicable in terms of bending fatigue and impact strength, and conducting an IST is highly recommended.
Bending fatigue strength of case-carburized helical gears with large helix angles up to 40 degrees
Mikiya Yamaoka,Motomu Tanaka,Masaya Kumada,Kengo Nojima,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12
Case-carburizing of helical gears with large helix angles may form too large hardened layers near the tooth width end on the acute angle side (ACUTE-END), and adversely affect the bending fatigue strength. We investigated the bending fatigue strength of casecarburized helical gears with large helix angles up to approximately 40° through a bending fatigue test, hardness test, and residual stress measurement. We found that the case-carburizing formed large hardened layers near ACUTE-END, reduced the compressive residual stress near ACUTE-END, and restricted the improvement of the bending fatigue strength in a meshing state where tooth root stress became large near ACUTE-END. Based on the obtained bending fatigue limits, we revealed that ISO 6336-3:2006 overestimated the rate of increase of the permissible circumferential loads for helix angles exceeding approximately 30°, and ISO/DIS 6336-3:2018 underestimated this rate for helix angles near 30°.