arXiv subjects

Paulo Freitas Gomes

Publications and source records attributed to Paulo Freitas Gomes.

6 recordsLinked to original sources

arXiv2024

New Coevolution Dynamic as an Optimization Strategy in Group Problem Solving

Coevolution on social models couples the time evolution of the network with the time evolution of the states of the agents. This paper presents a new coevolution dynamic allowing more than one rewiring on the network. We explore how this coevolution can be employed as an optimization strategy for problem-solving capability of task-forces. We used an agent-based model study how this new coevolution dynamic can help a group of agents whose task is to find the global maxima of NK fitness landscapes. Each agent can replace more than one neighbors, and this quantity is a tunable parameter in the model. These rewirings is a way for the agent to obtain information from individuals that were not previously part of its neighborhood. Our results showed that this tunable coevolution can indeed produce gain on the computational cost under certain circunstances. At low average degree (using a random network to connect the agents) and on easy landscape, more rewirings return lower cost, helping the agents to find the global maximum faster. However, at larger average degree and difficult landscape, the effect is more complex. At medium size systems, the coevolution brings optimal results when 3 or 4 neighbors are replaced.

nlin.CD↗

arXiv2023

Entanglement statistics of randomly interacting spins

We investigate the entanglement in the ground state of systems comprising two and three qubits with random interactions. Since the Hamiltonians also contain deterministic one-body terms, by varying the interaction strength, one can continuously interpolate between deterministic separable eigenstates and fully random entangled eigenstates, with non-trivial intermediate behavior. Entanglement strongly depends on the underlying topology of the interaction among the qubits. For a certain class of interactions GHZ entanglement is favoured by a non-separable collective interaction, while for fully separable pairwise interactions the ground states concentrate in the vicinity of W states.

quant-ph↗

arXiv2022

Modified SIS model applied to a Zombie apocalypse with terminators

In this work we study the dynamics in an apocalypse where the individuals can temporarily become zombies, returning to the living state again or die. We describe this dynamics using a modified version of the epidemic SIS model. The zombies can die when in contact with a terminator, which is part of the living people. To define the possible interactions we use an Erdös-Rènyi network and we calculate how the absorbing and active phase of the original SIS model is influenced by the average network degree. We also use the component and domain distribution of the network to understand how this influence occurs.

q-bio.PE↗

arXiv2022

Topological transition in a coupled dynamic in random networks

In this work, we study the topological transition on the associated networks in a model proposed by Saeedian et al. (Scientific Reports 2019 9:9726), which considers a coupled dynamics of node and link states. Our goal was to better understand the two observed phases, so we use another network structure (the so called random geometric graph - RGG) together with other metrics borrowed from network science. We observed a topological transition on the two associated networks, which are subgraphs of the full network. As the links have two possible states (friendly and non-friendly), we defined each associated network as composed of only one type of link. The (non) friendly associated network has (non) friendly links only. This topological transition was observed from the domain distribution of each associated network between the two phases of the system (absorbing and active). We also showed that another metric from network science called modularity (or assortative coefficient) can also be used as order parameter, giving the same phase diagram as the original order parameter from the seminal work. On the absorbing phase the absolute value of the modularity for each associated network reaches a maximum value, while on the active phase they fall to the minimum value.

physics.soc-ph↗

arXiv2018

Modal interferometer sensor optimized for transverse misalignment

We study the transmission coefficient and the transmitted power through an SMS sensor with transverse misalignment. We use the Finite Element Method to calculate the modes distribution by numerically solving the wave equation. The results show that the maximum transmission can be obtained when the misalignment is greater than zero due to the $n \neq m$ LP$_{nm}$ excited modes. Additionally, the transmitted power as function of the temperature shows that it is significant only in the aligned case.

physics.app-ph↗

arXiv2018

Epidemic SIR model on a face-to-face interaction network: new mobility induced phase transitions

In this work, we study the epidemic SIR model on a system which takes into consideration face-to-face interaction networks. This approach has been used as prototype to describe people interactions in different kinds of social organizations and, here, it is considered by means of three features of human interactions: the mobility, the duration of the interaction among people, and the dependence of the number of interactions of each person on the time evolution of the system. For this purpose, the initial configuration of the system is set as a regular square lattice where the nodes are the individuals which, in turn, are able to move in a random walk along the network. So, the connectivity among the individuals evolve with time and is defined by the positions of the individuals at each iteration. In a time unit, each individual is able move up to a distance $v$ creating different networks along the time evolution of the system. In addition, the individuals are interacting with each other only if they are within the interaction distance $δ$ and, in this case, they are considered as neighbors. If a given individual is interacting with other ones, he performs the random walk with a diffusion probability $ω$. Otherwise, the diffusion occurs with probability 1. The study was carried out through non-equilibrium Monte Carlo Simulations and we take into account the asynchronous updating scheme. The results show that, for a given $v>0$, there exist a critical line in the $(c, δ)$ space, where $c$ is the immunization rate. We also obtain the dynamic critical exponent $θ$ for some points belonging to this line and show that this model does not belong to the directed percolation universality class.

physics.soc-ph↗