arXiv subjects

Sakurako Tanida

Publications and source records attributed to Sakurako Tanida.

7 recordsLinked to original sources

arXiv2026

Effective attractive and repulsive interactions behind lift synchronization

Synchronization is a ubiquitous phenomenon in nonequilibrium systems. One intriguing example found in every-day life is lifts installed next to each other, that move closely and arrive almost simultaneously during a busy time. However, the basic mechanism behind this lift synchronization is yet to be elucidated. Here, we investigate the effective interaction acting between the lifts quantitatively. Through the analysis on the time-series data obtained by numerically solving a rule-based discrete model of lifts, in which passengers at each floor show up stochastically and call a lift that is expected to arrive first, we find that the effective interaction acting between the lifts consists of not only attraction but also repulsion. By changing the parameters of the rule-based model, we are successful to tune the ratio of these competing interactions and to control the dynamics of lifts, realising the transition between in-phase and anti-phase synchronizations. Our strategy is applicable to the data of real lifts, and thus it is expected to help controlling lift systems. We believe that this study provides a novel approach to design optimal transportation, which is of great importance in improving sustainability of social systems.

nlin.AO↗

arXiv2026

Conflict Avoidance in Pedestrian Merging in Controlled Experiments by Variance Indicator

Pedestrian congestion at corridor intersections often originates from localized fluctuations in motion rather than from a macroscopic collapse of flow. Understanding pedestrian instability at corridor intersections remains challenging because existing studies mainly rely on density, average speed, or flow-based measures and limited datasets, making it difficult to separate geometric turning effects from interaction induced fluctuations in merging flows. In particular, the mechanism underlying the turning angle dependence in T junctions has not been resolved. Here, we analyze more than 300 controlled experiments conducted in L corridors with turning only and T corridors with turning and merging. Using Voronoi-based speed variance $V_s$ and velocity variance $V_v$, we systematically compare geometric and interaction effects. $V_s$ effectively captures interaction driven instability, while $V_v$ reflects directional adjustments due to geometry. The comparison reveals distinct fluctuation mechanisms and identifies a critical transition near $90°$, demonstrating the advantage of variance-based indicators for diagnosing pedestrian dynamics.

physics.soc-ph↗

arXiv2025

Synchronization in bus systems with partially overlapping routes

In an increasingly interconnected world, understanding congestion-related phenomena in transportation and their underlying mechanisms is crucial for improving efficiency. As the transportation system becomes denser, different modes of transportation have more opportunities to interact with each other, giving rise to emergent dynamics that simple models cannot explain. In this study, we investigate the synchronized motion of indirectly coupled transportation modes. We develop a numerical simulation model on a one-dimensional periodic lattice, where each point represents a bus station. In this system, two types of buses operate: multiple local buses with non-overlapping routes, each serving a specific zone, and a single global bus that partially overlaps with the routes of the local buses. We perform numerical simulations to examine how close the arrival times of these buses are to each other -- that is, how synchronized their motions are. When the number of zones is two, three, or five, robust synchronization occurs not only between the global bus and the local buses, but also among the local buses themselves. In contrast, no synchronization is found for other numbers of zones. We developed a mathematical model using self-consistent equations and found that two distinct arrival patterns at the terminals must be considered. A stability analysis reveals which pattern is ultimately realized in the simulations. Our results show that transportation modes can exhibit coherent motion even when sharing only partial or no direct route overlaps. This outcome highlights that emergent behavior depends not only on local interactions but is also strongly shaped by the system's overall structural configuration.

physics.soc-ph↗

arXiv2022

The synchronization of elevators when not all passengers will ride the first-arriving elevator

The cluster motion of busy multiple elevators is considered to be one of the synchronization phenomena of autonomous oscillators. In this study, we used numerical simulations to quantitatively explore differences in the elevators' dynamics during down peaks under isolated and coupled conditions. We introduced the proportion of passengers who are set to ride the first-arriving elevator as a control parameter and investigated the behaviors of elevators when the proportions of those passengers and the inflow of passengers were varied. When we increased the inflow of passengers, the synchronization was promoted and the round-trip time increased. On the other hand, when we increased the proportion of those passengers, the synchronization was promoted while the round-trip time decreased. To elucidate the relationship between the parameters and dynamics and clarify the mechanism, we established simple mathematical models; First, we reproduced the round-trip time by a self-consistent equation considering the inflow of passengers and the proportion of passengers set to ride the first-arriving elevator. Then, we estimated an order parameter of the synchronization.

nlin.AO↗

arXiv2021

Arranging the order of passengers on the boarding bridge to reduce the boarding time for single-aisle aircraft

Reducing the aircraft boarding time is a common problem not only for airlines, but also for passengers and airports. Group boarding is a popular boarding strategy that separates the passengers into several groups and those groups, which are then called in a certain order. Group boarding can reduce the boarding time compared with that in random order boarding; however, it is insufficient in several real scenarios because the passengers are not separated strictly into groups. In this paper, we propose a boarding strategy that arranges the order of the boarding passengers at the boarding gate. Although this approach appears more time-consuming, we show that such a rearrangement can be applied efficiently to the waiting queue of a single-aisle aircraft. We quantitatively demonstrate the boarding times for various patterns of this approach and discuss the mechanism underlying the reduction of boarding time. This strategy is a promising approach to reduce boarding times and can replace the conventional boarding strategy.

physics.soc-ph↗

arXiv2021

Dynamic behavior of elevators under random inflow of passengers

Elevators can be regarded as oscillators driven by the calls of passengers who arrive randomly. We study the dynamic behavior of elevators during the down peak period numerically and analytically. We assume that new passengers arrive at each floor according to a Poisson process and call the elevators to go down to the ground floor. We numerically examine how the round-trip time of a single elevator depends on the inflow rate of passengers at each floor and reproduce it by a self-consistent equation considering the combination of floors where call occurs. By setting an order parameter, we show that the synchronization of two elevators occurs irrespective of final destination (whether the elevators did or did not go to the top floor). It indicates that the spontaneous ordering of elevators emerges from the Poisson noise. We also reproduce the round-trip time of two elevators by a self-consistent equation considering the interaction through the existence of passengers and the absence of volume exclusion. Those results suggest that such interaction stabilizes and characterizes the spontaneous ordering of elevators.

cond-mat.stat-mech↗

arXiv2018

Gliding filament system giving both orientational order and clusters in collective motion

Active matter consists of self-propelled elements exhibits fascinating collective motions ranging from biological to artificial systems. Among wide varieties of active matter systems, reconstituted bio-filaments moving on molecular motor turf interacting purely by physical interactions provides the fundamental test ground for understanding biological motility. However, until now, multi-filament collisions,depletion agents or binding molecules has been required for the emergence of ordered patterns in motility assay. Thus, whether simple physical interactions during collisions such as steric effect without depletion nor binding agents are sufficient or not for producing ordered patterns in motility assays remains still elusive. In this article, we constructed a motility assay purely consists of kinesin motor and microtubule in which the frequency of binary collision can be controlled without using depletion nor binding agents. By controlling strength of steric interaction and density of microtubules, we found different states; disordered state, long-range orientationally ordered state, liquid-gas-like phase separated state, and transitions between them. We found that a balance between cross over and aligning events in collisions controls transition from disorder to global ordered state, while excessively strong steric effect leads to the phase separated clusters. Furthermore, macroscopic chiral symmetry breaking observed as a global rotation of nematic order observed in this experiment could be attributed to the chirality at molecular level. Numerical simulations in which we change strength of volume exclusion reproduce these experimental results. Moreover, it reveals the transition from long-range alignment to nematic bands then to aggregations. This study may provide new insights into dynamic ordering by self-propelled elements through a purely physical interaction.

cond-mat.soft↗