Multi-objective NSGA-II based community detection using dynamical evolution social network

Community detection is becoming a highly demanded topic in social networking-based applications. It involves finding the maximum intraconnected and minimum inter-connected sub-graphs in given social networks. Many approaches have been developed for community’s detection and less of them have focused on the dynamical aspect of the social network. The decision of the community has to consider the pattern of changes in the social network and to be smooth enough. This is to enable smooth operation for other community detection dependent application. Unlike dynamical community detection Algorithms, this article presents a non-dominated aware searching Algorithm designated as non-dominated sorting based community detection with dynamical awareness (NDS-CD-DA). The Algorithm uses a non-dominated sorting genetic algorithm NSGA-II with two objectives: modularity and normalized mutual information (NMI). Experimental results on synthetic networks and real-world social network datasets have been compared with classical genetic with a single objective and has been shown to provide superiority in terms of the domination as well as the convergence. NDS-CD-DA has accomplished a domination percentage of 100% over dynamic evolutionary community searching DECS for almost all iterations.

A New Thought Experiment on Relativistic Length Contraction

Relativistic length contraction is revisited and a simple but new thought experiment is proposed in which an apparent asymmetric situation is developed between two different inertial frames regarding detection of light that comes from a chamber to an adjacent chamber through a movable slit. The proposed experiment does not involve gravity, rigidity or any other dynamical aspect apart from the kinematics of relative motion; neither does it involve any kind of nonuniformity in motion. The resolution of the seemingly paradoxical situation has finally been discussed.

A Validated Study of a Modified Shallow Water Model for Strong Cyclonic Motions and Their Structures in a Rotating Tank

A joint theoretical and numerical study was carried out to investigate the fluid dynamical aspect of the motion of a vortex generated in a rotating tank with a sloping bottom. This study aims at understanding the evolution of strong cyclonic motions on a β-plane in the Northern Hemisphere. The strong cyclonic vortices were characterized by four nondimensional parameters which were derived through a scale analysis of the depth variations of fluid. By simplifying the model flow field and the prototype flow field, respectively, through the conservation of potential vorticity, two sets of dynamic similarity conditions are derived. This study proposed a sophisticated modified shallow water model (MSWM) to investigate the flow features of such strong vortices. A detailed numerical calculation adopted by multidimensional positive definite advection transport algorithm (MPDATA) was carried out to validate those effects considered in the MSWM model, including sloping bottom, parabolic free surface deformation, and viscous dissipation. Close agreements were found between the experimental and numerical results, including the streamlines patterns and the vortex trajectory. Comprehensive simulations for strong cyclonic vortices over different sloping bottoms were investigated to understand the impact of planetary β effect on vortex. The results calculated by MSWM demonstrate a variety of flow features of interactions between the primary vortex and induced secondary Rossby wave wakes that were essential and prominent in environmental geophysical flows.

Kibble–Zurek mechanism in the Ising Field Theory

The Kibble--Zurek mechanism captures universality when a system is driven through a continuous phase transition. Here we study the dynamical aspect of quantum phase transitions in the Ising Field Theory where the quantum critical point can be crossed in different directions in the two-dimensional coupling space leading to different scaling laws. Using the Truncated Conformal Space Approach, we investigate the microscopic details of the Kibble--Zurek mechanism in terms of instantaneous eigenstates in a genuinely interacting field theory. For different protocols, we demonstrate dynamical scaling in the non-adiabatic time window and provide analytic and numerical evidence for specific scaling properties of various quantities. In particular, we argue that the higher cumulants of the excess heat exhibit universal scaling in generic interacting models for a slow enough ramp.

Holographic de Sitter spacetime and quantum corrections to the cosmological constant

A dynamical aspect of quantum gravity on de Sitter spacetime is investigated by holography and the de Sitter/conformal field theory correspondence. We show that de Sitter spacetime emerges from a free Sp($N$) vector model by complexifying the ghost fields and course-graining them by flow equation in parallel to the imaginary axis. We confirm that the emergence of de Sitter spacetime is ensured by conformal symmetry. We also compute the quantum corrections to the cosmological constant up to the next-to-leading order of the $1/N$ expansion in a proposed holographic approach. As a result the sub-leading corrections have the opposite sign to the classical value. This implies that a quantum gravity on de Sitter spacetime is perturbatively stable and quantum effects make the universe flatter and the cosmological constant smaller.

Central Configurations and Action Minimizing Orbits in Kite Four-Body Problem

In the current article, we study the kite four-body problems with the goal of identifying global regions in the mass parameter space which admits a corresponding central configuration of the four masses. We consider two different types of symmetrical configurations. In each of the two cases, the existence of a continuous family of central configurations for positive masses is shown. We address the dynamical aspect of periodic solutions in the settings considered and show that the minimizers of the classical action functional restricted to the homographic solutions are the Keplerian elliptical solutions. Finally, we provide numerical explorations via Poincaré cross-sections, to show the existence of periodic and quasiperiodic solutions within the broader dynamical context of the four-body problem.

Highlighting growth regulation processes in fish populations by a simplex simulation approach: application to Merluccius hubbsi stocks in the Southwestern Atlantic

A new simplex-based simulation approach (Spx) was developed to highlight multidirectional and multi-scale relationships between morphometric variables helping to functionally differentiate biological (fish) groups for better stocks definition and monitoring. Application concerned Merluccius hubbsi sampled in 1968–1972 and 2004 in six Southwestern Atlantic areas. Simulation results highlighted negative trends opposing front to back compartments indicating competition for body biomass distribution. However, top and bottom parts within these compartments were positively correlated indicating cooperative processes in favour of target local growth regulation. Positive and negative trends of growth regulation were also highlighted at lower body scale, notably between smaller components constituting body front compartment. On a geographical scale, average regulation levels of same morphometric variables showed monotonic or alternated variations between successive fish groups. This highlighted target and modulated growth regulations governing biomass distribution in different body parts by geographical-dependent ways. Under dynamical aspect (1968–1972 vs. 2004), growth regulation of mouth tended to increase with time leading to conclude on morphometric responses of M. hubbsi to overfishing pressure. Spx results were confirmed by several traditional approaches which showed less integrative aspect.

Demographical Ageing of the EU Member States’ Societies

A spatial differentiation of the level of demographical senility was illustrated in the study, along with determination of dynamics of the European Union Member States ageing process (EU 27). The research period included years 1996-2016. The measures of demographical senility were used in the static and dynamical aspect. Country grouping due to the level of demographical senility advancement was performed based on statistical measures. A significant differentiation of the demographical senility level and population ageing process in the spatial system were found. The highest degree of demographical senility advancement was observed in the countries of “the old” Union but the greatest dynamics of this process was shown in the case of new Member States, including Poland and Baltic States.