DSpace Repository :: Browsing by Author "Parisi, Daniel"

Browsing by Author "Parisi, Daniel"

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Active particles with desired orientation flowing through a bottleneck
(2018-12) Parisi, Daniel; Cruz Hidalgo, Raúl; Zuriguel, Iker
"We report extensive numerical simulations of the flow of anisotropic self-propelled particles through a constriction. In particular, we explore the role of the particles’ desired orientation with respect to the moving direction on the system flowability. We observe that when particles propel along the direction of their long axis (longitudinal orientation) the flow-rate notably reduces compared with the case of propulsion along the short axis (transversal orientation). And this is so even when the effective section (measured as the number of particles that are necessary to span the whole outlet) is larger for the case of longitudinal propulsion. This counterintuitive result is explained in terms of the formation of clogging structures at the outlet, which are revealed to have higher stability when the particles align along the long axis. This generic result might be applied to many different systems flowing through bottlenecks such as microbial populations or different kind of cells. Indeed, it has already a straightforward connection with recent results of pedestrian (which self-propel transversally oriented) and mice or sheep (which self-propel longitudinally oriented)."
AntSwarm
(2012) Goldberg, Daniel; Liendro, José Indalecio; Parisi, Daniel
"El objetivo general del presente trabajo final es aplicar y desarrollar las herramientas de procesamiento de imágenes y video necesarias para poder analizar los registros adquiridos en los experimentos particulares."
Clogging transition of vibration-driven vehicles passing through constrictions
(2017-12) Patterson, Germán; Fierens, Pablo Ignacio; Sangiuliano Jimka, Federico; König, Pablo; Garcimartín, Ángel; Zuriguel, Iker; Pugnaloni, Luis Ariel; Parisi, Daniel
"We report experimental results on the competitive passage of elongated self-propelled vehicles rushing through a constriction. For the chosen experimental conditions, we observe the emergence of intermittencies similar to those reported previously for active matter passing through narrow doors. Noteworthy, we find that, when the number of individuals crowding in front of the bottleneck increases, there is a transition from an unclogged to a clogged state characterized by a lack of convergence of the mean clog duration as the measuring time increases. It is demonstrated that this transition—which was reported previously only for externally vibrated systems such as colloids or granulars—appears also for self-propelled agents. This suggests that the transition should also occur for the flow through constrictions of living agents (e.g., humans and sheep), an issue that has been elusive so far in experiments due to safety risks."
Continuous-space automaton model for pedestrian dynamics
(2011-05-11) Baglietto, Gabriel; Parisi, Daniel
An off-lattice automaton for modeling pedestrian dynamics is presented. Pedestrians are represented by disks with variable radius that evolve following predefined rules. The key feature of our approach is that although positions and velocities are continuous, forces do not need to be calculated. This has the advantage that it allows using a larger time step than in force-based models. The room evacuation problem and circular racetrack simulations quantitatively reproduce the available experimental data, both for the specific flow rate and for the fundamental diagram of pedestrian traffic with an outstanding performance. In this last case, the variation of two free parameters (r min and rmax) of the model accounts for the great variety of experimental fundamental diagrams reported in the literature. Moreover, this variety can be interpreted in terms of these model parameters.
Cryptobot: creación de base de datos y estudio de series temporales de criptomonedas
(2019-12-18) Oviedo Candelaresi, Fernán Darío; Fratoni, Axel; Parisi, Daniel
"Existe una plataforma de intercambio de criptomonedas llamada HitBTC que provee una API para interactuar con los mercados. El objetivo de este trabajo fue desarrollar un sistema de software que permitiera recabar información del mercado de forma automática a lo largo del tiempo, analizar esta información para caracterizar el comportamiento del mercado e implementar estrategias de decisión automática para ejecutar operaciones de compraventa."
Data-driven simulation for pedestrian avoiding a fixed obstacle
(2019-07) Martin, Rafael F.; Parisi, Daniel
"Data-driven simulation of pedestrian dynamics is an incipient and promising approach for building reliable microscopic pedestrian models. We propose a methodology based on generalized regression neural networks, which does not have to deal with a huge number of free parameters as in the case of multilayer neural networks. Although the method is general, we focus on the one pedestrian—one obstacle problem. The proposed model allows us to simulate the trajectory of a pedestrian avoiding an obstacle from any direction."
Data-driven simulation of pedestrian collision avoidance with a nonparametric neural network
(2020-02) Martin, Rafael F.; Parisi, Daniel
"Data-driven simulation of pedestrian dynamics is an incipient and promising approach for building reliable microscopic pedestrian models. We propose a methodology based on generalized regression neural networks, which does not have to deal with a huge number of free parameters as in the case of multilayer neural networks. Although the method is general, we focus on the one pedestrian - one obstacle problem. Experimental data were collected in a motion capture laboratory providing high-precision trajectories. The proposed model allows us to simulate the trajectory of a pedestrian avoiding an obstacle from any direction. Together with the methodology specifications, we provide the data set needed for performing the simulations of this kind of pedestrian dynamic system."
Effect of physical distancing on the speed-density relation in pedestrian dynamics
(2021-04) Echeverría Huarte, Iñaki; Garcimartín, Ángel; Parisi, Daniel; Martín-Gómez, César
"We report experimental results of the speed-density relation emerging in pedestrian dynamics when individuals keep a prescribed safety distance among them. To this end, we characterize the movement of a group of people roaming inside an enclosure varying different experimental parameters: (i) global density, (ii) prescribed walking speed, and (iii) suggested safety distance. Then, by means of the Voronoi diagram we are able to compute the local density associated to each pedestrian, which is afterward correlated with its corresponding velocity at each time. In this way, we discover a strong dependence of the speed-density relation on the experimental conditions, especially with the (prescribed) free speed. We also observe that when pedestrians walk slowly, the speed-density relation depends on the global macroscopic density of the system, and not only on the local one. Finally, we demonstrate that for the same experiment, each pedestrian follows a distinct behavior, thus giving rise to multiple speed-density curves."
Effect of physical distancing on the speed–density relation in pedestrian dynamics
(2021-04) Echeverría Huarte, Iñaki; Garcimartín, Ángel; Parisi, Daniel; Cruz Hidalgo, R.; Martín-Gómez, César; Zuriguel, Iker
"We report experimental results of the speed-density relation emerging in pedestrian dynamics when individuals keep a prescribed safety distance among them. To this end, we characterize the movement of a group of people roaming inside an enclosure varying different experimental parameters: (i) global density, (ii) prescribed walking speed, and (iii) suggested safety distance. Then, by means of the Voronoi diagram we are able to compute the local density associated to each pedestrian, which is afterward correlated with its corresponding velocity at each time. In this way, we discover a strong dependence of the speed-density relation on the experimental conditions, especially with the (prescribed) free speed. We also observe that when pedestrians walk slowly, the speed-density relation depends on the global macroscopic density of the system, and not only on the local one. Finally, we demonstrate that for the same experiment, each pedestrian follows a distinct behavior, thus giving rise to multiple speed-density curves."
Elongated self-propelled particles roaming a closed arena present financial stylized facts
(2019-07) Patterson, Germán; Parisi, Daniel
"We report the existence of financial stylized facts in a system of mechanical vehicles driven by vibration (VDV). The VDVs are restricted to a closed geometry that is composed of two chambers connected by an opening which allows a continuous flow of agents between the two regions. We studied the temporal evolution of the density of particles around the opening and made a statistical comparison with the price evolution of bitcoin (BTC). We found remarkable similarities between these two systems enabling us to study financial systems from a new perspective."
Flow of pedestrians through narrow doors with dierent competitiveness
(2016) Garcimartín, Ángel; Parisi, Daniel; Pastor, José Martín; Martín-Gómez, César; Zuriguel, Iker
"We report a thorough analysis of the intermittent flow of pedestrians through a narrow door. The observations include five diferent sets of evacuation drills with which we have investigated the efect of door size and competitiveness on the flow dynamics. Although the outcomes are in general compatible with the existence of the faster-is-slower efect, the temporal evolution of the instantaneous flow rate provides evidence of new features. These stress the crucial role of the number of people performing the tests, which has an influence on the obtained results. Once the transients at the beginning and end of the evacuation are removed, we have found that the time lapses between the passage of two consecutive pedestrians display heavy-tailed distributions in all the scenarios studied. Meanwhile, the distribution of burst sizes decays exponentially; this can be linked to a constant probability of finding a long-lasting clog during the evacuation process. Based on these results, a discussion is presented on the caution that should be exercised when measuring or describing the intermittent flow of pedestrians through narrow doors."
Fusion of magnetic and WiFi fingerprints for indoor positioning
(2018) Grisales Campeón, Juan Pablo; López, Sebastián; de Jesús Meleán, Sergio R.; Moldovan, Horatiu; Parisi, Daniel; Fierens, Pablo Ignacio
"WiFi received signal strength (RSS) and magnetic field intensity are common measures for indoor localization because they are readily available on most mobile devices. There is a vast literature on smartphone positioning using RSS and it has been widely implemented in real-world scenarios in the last two decades. There is much work done on localization aided by magnetic field measurements. We have recently evaluated the accuracy of RSS-based positioning applying state-of-the-art algorithms to measurements in a well-controlled experimental setup. In this paper, we extend this work to assess the accuracy improvements achievable by fusing WiFi and magnetic field information. We show that accuracy improvements of up to 30% are possible."
Future virtual particle method for pedestrian navigation
(2015) Castiglione, Gonzalo; Marseillan, Agustín; Parisi, Daniel
"This paper presents an avoidance collision method based in pedestrian self governed decisions, by calculating the position of every pedestrian in the future, a given pedestrian can adjust his velocity vector to avoid col-lisions instead of being affected by a repulsive force."
Indoor positioning based on RSSI of WiFi signals: how accurate can it be?
(2019-02-20) Grisales Campeón, Juan Pablo; López, Sebastián; de Jesús Meleán, Sergio R.; Parisi, Daniel; Fierens, Pablo Ignacio; Moldovan, Herman
"There is abundant literature on positioning systems based on WiFi signals. Most of the systems with off-the-shelf hardware use RSSI measurements. In this paper, we try to determine the highest achievable accuracy of such systems. Instead of resorting to a theoretical analysis, e.g., Cram´er-Rao or Ziv-Zakai bounds, we apply state-of-the-art localization algorithms to measurements in a well-controlled experimental setup. We conclude that an accuracy of less than 1 meter seems unrealistic."
Influence of bottleneck lengths and position on simulated pedestrian egress
(2017-01) Parisi, Daniel; Patterson, Germán
"In this paper, the problem of pedestrian egress under di erent geometries is studied by means of two numerical models. The length of the bottleneck after the exit and the distance of the exit to the lateral wall of a squared room are investigated. Both models show that an increase in the bottleneck length increases the evacuation time by more than 20%, for any exit position. Hence, a bottleneck length tending to zero is the best choice. On the contrary, the results of moving the exit closer to the lateral wall are different in both models and, thus, its convenience cannot be stated. To unveil whether this layout modi cation is favorable, experimental data are required. Moreover, the discrepancy between models indicates that they should be validated considering several scenarios."
Pedestrian collective motion in competitive room evacuation
(2017-12) Garcimartín, Ángel; Pastor, José Martín; Martín-Gómez, César; Parisi, Daniel; Zuriguel, Iker
"When a sizable number of people evacuate a room, if the door is not large enough, an accumulation of pedestrians in front of the exit may take place. This is the cause of emerging collective phenomena where the density is believed to be the key variable determining the pedestrian dynamics. Here, we show that when sustained contact among the individuals exists, density is not enough to describe the evacuation, and propose that at least another variable-such as the kinetic stress-is required. We recorded evacuation drills with different degrees of competitiveness where the individuals are allowed to moderately push each other in their way out. We obtain the density, velocity and kinetic stress fields over time, showing that competitiveness strongly affects them and evidencing patterns which have been never observed in previous (low pressure) evacuation experiments. For the highest competitiveness scenario, we detect the development of sudden collective motions. These movements are related to a notable increase of the kinetic stress and a reduction of the velocity towards the door, but do not depend on the density."
Pedestrian collision avoidance with a local dynamic goal
(2018-08-21) Martin, Rafael F.; Parisi, Daniel
"We present here a general formalism for equipping simulated pedestrians with an avoidance mechanism. The central idea is to use a short-range target which is adjusted dynamically depending on the environment and thus modulating the desired velocity of the agent. This formulation can be implemented over any type of existing pedestrian model, being force-based or rule-based. As an example, we implement a simple instance of the formulation which is adjusted to reproduce previous reported and available experimental data of collision avoidance in scenarios of low density. The proposed minimal model shows good agreement with the real trajectories and other macroscopic observables."
Pedestrian dynamics at the running of the bulls evidences an inaccessible region in the fundamental diagram
(2021-09) Parisi, Daniel; Sartorio, Alan G.; Colonnello, Joaquín R.; Garcimartín, Ángel; Pugnaloni, Luis Ariel; Zuriguel, Iker
"We characterize the dynamics of runners in the famous “Running of the Bulls” Festival by computing the individual and global velocities and densities, as well as the crowd pressure. In contrast with all previously studied pedestrian systems, we unveil a unique regime in which speed increases with density that can be understood in terms of a time-dependent desired velocity of the runners. Also, we discover the existence of an inaccessible region in the speed–density state diagram that is explained by falls of runners. With all these ingredients, we propose a generalization of the pedestrian fundamental diagram for a scenario in which people with different desired speeds coexist."
People counting using visible and infrared images
(2020-10-19) Biagini, Martín; Filipic, Joaquín; Parisi, Daniel
"We propose the use of convolutional neural networks that consider as input four channels images (RGB+IR) for counting and positioning people in images. Our data set was made of images based on photographs taken from a drone using a dual FLIR camera. Comparison between 3 (RGB) and 4 (RGB+IR) channels are studied for different lightning conditions. The four channel network performs better in all situations, particularly in cases of poor visible illumination that can be found in real night scenarios. The average precision of this network on a testing data set (independent from the training one) is approximately 1 cm in nding the positions of pedestrians (from 15 and 30 m altitude images) and 0.0001% in the relative counting error."
People counting using visible and infrared images
(2020-10) Biagini, Martín; Filipic, Joaquín; Mas, Ignacio; Pose, Claudio D.; Giribet, Juan I.; Parisi, Daniel
"We propose the use of convolutional neural networks (CNN) for counting and positioning people in visible and infrared images. Our data set is made of semi-artificial images created from real photographs taken from a drone using a dual FLIR camera. We compare the performance between CNN’s using 3 (RGB) and 4 (RGB+IR) channels, both under different lighting conditions. The 4-channel network responds better in all situations, particularly in cases of poor visible illumination that can be found in night scenarios. The proposed methodology could be applied to real situations when an extensive databank of 4-channel images will be available."

Browsing by Author "Parisi, Daniel"

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