In silico characterization of asymmetric active polar emulsions
In this paper an in silico study of the behavior of an active polar emulsion is reported, focusing on the case of a highly off-symmetric ratio between the polar (active) and passive components, both for the extensile and contractile case. In absence of activity the system is characterized by an hexatic-ordered droplets phase. We find that small extensile activity is able to enhance the hexatic order in the array of droplets with respect to the passive case, while increasing activity aster-like rotating droplets appear.
Turing patterns in a reaction-diffusion system modeling hunting cooperation
A reaction-diffusion system governing the prey-predator interaction with hunting cooperation is investigated.
Definitive boundedness of solutions is proved via the existence of positive invariants and attractive sets.
Linear stability of the coexistence equilibria is performed and conditions guaranteeing
the occurrence of Turing instability are found. Numerical simulations on the obtained results are provided.
Curvature dynamics and long-range effects on fluid-fluid interfaces with colloids
We investigate the dynamics of a phase-separating binary fluid, containing colloidal dumbbells anchored to the fluid-fluid interface. Extensive lattice Boltzmann-immersed boundary method simulations reveal that the presence of soft dumbbells can significantly affect the curvature dynamics of the interface between phase-separating fluids, even though the coarsening dynamics is left nearly unchanged. In addition, our results show that the curvature dynamics exhibits distinct non-local effects, which might be exploited for the design of new soft mesoscale materials.
Robust design optimization for egressing pedestrians in unknown environments
In this paper, we deal with a group variable in size of pedestrians moving in a unknown confined environment and searching for an exit. Pedestrian dynamics are simulated by means of a recently introduced microscopic (agent-based) model, characterized by an exploration phase and an egress phase. First, we study the model to reveal the role of its main parameters and its qualitative properties.
Bootstrap AMG for Spectral Clustering
Graph Laplacian is a popular tool for analyzing graphs, in particular in graph partitioning and clustering. Given a notion of similarity (via an adjacency matrix), graph clustering refers to identifying different groups such that vertices in the same group are more similar compared to vertices across different groups. Data clustering can be reformulated in terms of a graph clustering problem when the given set of data is represented as a graph, also known as similarity graph.
Efficient Algebraic Multigrid Preconditioners on Clusters of GPUs
Many scientific applications require the solution of large and sparse linear systems of equations using Krylov subspace methods; in this case, the choice of an effective preconditioner may be crucial for the convergence of the Krylov solver. Algebraic MultiGrid (AMG) methods are widely used as preconditioners, because of their optimal computational cost and their algorithmic scalability. The wide availability of GPUs, now found in many of the fastest supercomputers, poses the problem of implementing efficiently these methods on high-throughput processors.
Assessment of quality of MIPAS ESA L2 products
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The analysis of MIPAS measurements allows to study the temporal evolution of numerous species of interest for the study of the ozone in the stratosphere, pollutants and many green-house gases.
The objective of the MIPAS Quality Working Group is to improve the quality of the MIPAS products through a fruitful collaboration among spectroscopists, Level 1, Level 2, and validation teams.
Preliminary assessment of the quality of Methyl chloride (CH3Cl) from MIPAS on ENVISAT measurements
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 on board the ENVISAT satellite. The fruitful collaboration among spectroscopists, Level 1, Level 2, and validation teams in the frame of the MIPAS Quality Working Group has recently led to the implementation of significant changes in both ESA Level 1 and Level 2 processors, as well as in the spectroscopic database and in some absorption cross-sections.