2,111 research outputs found
Model of human collective decision-making in complex environments
A continuous-time Markov process is proposed to analyze how a group of humans
solves a complex task, consisting in the search of the optimal set of decisions
on a fitness landscape. Individuals change their opinions driven by two
different forces: (i) the self-interest, which pushes them to increase their
own fitness values, and (ii) the social interactions, which push individuals to
reduce the diversity of their opinions in order to reach consensus. Results
show that the performance of the group is strongly affected by the strength of
social interactions and by the level of knowledge of the individuals.
Increasing the strength of social interactions improves the performance of the
team. However, too strong social interactions slow down the search of the
optimal solution and worsen the performance of the group. In particular, we
find that the threshold value of the social interaction strength, which leads
to the emergence of a superior intelligence of the group, is just the critical
threshold at which the consensus among the members sets in. We also prove that
a moderate level of knowledge is already enough to guarantee high performance
of the group in making decisions.Comment: 12 pages, 8 figues in European Physical Journal B, 201
Loading-unloading hysteresis loop of randomly rough adhesive contacts
In this paper we investigate the loading and unloading behavior of soft
solids in adhesive contact with randomly rough profiles. The roughness is
assumed to be described by a self-affine fractal on a limited range of
wave-vectors. A spectral method is exploited to generate such randomly rough
surfaces. The results are statistically averaged, and the calculated contact
area and applied load are shown as a function of the penetration, for loading
and unloading conditions. We found that the combination of adhesion forces and
roughness leads to a hysteresis loading-unloading loop. This shows that energy
can be lost simply as a consequence of roughness and van der Waals forces, as
in this case a large number of local energy minima exist and the system may be
trapped in metastable states. We numerically quantify the hysteretic loss and
assess the influence of the surface statistical properties and the energy of
adhesion on the hysteresis process.Comment: 8 pages, 9 figures, published on Physical Review E, Volume 92, Issue
6, 8 December 2015, Article number 06240
Theory of Reciprocating Contact for Viscoelastic Solids
A theory of reciprocating contacts for linear viscoelastic materials is
presented. Results are discussed for the case of a rigid sphere sinusoidally
driven in sliding contact with a viscoelastic half-space. Depending on the size
of the contact, the frequency and amplitude of the reciprocating motion, and on
the relaxation time of the viscoelastic body, we establish that the contact
behavior may range from the steady-state viscoelastic solution, in which
traction forces always oppose the direction of the sliding rigid punch, to a
more elaborate trend, never observed before, which is due to the strong
interaction between different regions of the path covered during the
reciprocating motion. Practical implications span a number of applications,
ranging from seismic engineering to biotechnology.Comment: 8 pages, 5 figures, accepted for publication on Physical Review E,
March 22, 201
A Low-Cost Easy-Operation Hexapod Walking Machine
This paper presents the mechanical design of an hybrid hexapod walking machine that has been designed and built at LARM: Laboratory of Robotics and Mechatronics in Cassino. Basic characteristics are investigated in order to design a leg system with suitable low-cost modular components. Moreover, special care has been addressed in proposing an architecture that can be easily operated by a PLC with on-off logic. Experimental tests are reported in order to show feasibility and operational capability of proposed design
Foreword to the Special Issue on the Computational Kinematics Conference, CK2017
Computational Kinematics is a wide field of science addressing applications ranging from robotics to mechanics, computer science, mathematics and computer graphics
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