Real-time edge tracking using a tactile sensor

Object recognition through the use of input from multiple sensors is an important aspect of an autonomous manipulation system. In tactile object recognition, it is necessary to determine the location and orientation of object edges and surfaces. A controller is proposed that utilizes a tactile sensor in the feedback loop of a manipulator to track along edges. In the control system, the data from the tactile sensor is first processed to find edges. The parameters of these edges are then used to generate a control signal to a hybrid controller. Theory is presented for tactile edge detection and an edge tracking controller. In addition, experimental verification of the edge tracking controller is presented

Sustainability, stakeholders and business. Editorial

Over the past 20 years, there has been an increasing attention on the drivers of value in organizations. Both the strategic management literature and practice have remarked the importance for managers to be aware of the impact of firm activities, products and services on either the external and internal environment and, more generally, on all firm stakeholders. The emergence of the notions of “sustainable development” and “sustainability” reflects a profound change in global thinking, which forces firms to move beyond trade-offs between business and society

Active Brownian Motion Tunable by Light

Active Brownian particles are capable of taking up energy from their environment and converting it into directed motion; examples range from chemotactic cells and bacteria to artificial micro-swimmers. We have recently demonstrated that Janus particles, i.e. gold-capped colloidal spheres, suspended in a critical binary liquid mixture perform active Brownian motion when illuminated by light. In this article, we investigate in some more details their swimming mechanism leading to active Brownian motion. We show that the illumination-borne heating induces a local asymmetric demixing of the binary mixture generating a spatial chemical concentration gradient, which is responsible for the particle's self-diffusiophoretic motion. We study this effect as a function of the functionalization of the gold cap, the particle size and the illumination intensity: the functionalization determines what component of the binary mixture is preferentially adsorbed at the cap and the swimming direction (towards or away from the cap); the particle size determines the rotational diffusion and, therefore, the random reorientation of the particle; and the intensity tunes the strength of the heating and, therefore, of the motion. Finally, we harness this dependence of the swimming strength on the illumination intensity to investigate the behaviour of a micro-swimmer in a spatial light gradient, where its swimming properties are space-dependent

D{\cal D}-deformed harmonic oscillators

We analyze systematically several deformations arising from two-dimensional harmonic oscillators which can be described in terms of $\cal{D}$-pseudo bosons. They all give rise to exactly solvable models, described by non self-adjoint hamiltonians whose eigenvalues and eigenvectors can be found adopting the quite general framework of the so-called $\cal{D}$-pseudo bosons. In particular, we show that several models previously introduced in the literature perfectly fit into this scheme.Comment: in press in International Journal of Theoretical Physic

Trade--Off Between Seismic Source Detail and Crustal Heterogeneities in Spherical 3D Finite Element Modeling: the 2004 Sumatra Earthquake case-study

Finite Element methods (FEMs) are a powerful numerical simulation tool for modeling seismic events as they allow to solve three-dimensional complex models. We used a 3D Finite Element approach to evaluate the co-seismic displacement eld produced by the devastating 2004 Sumatra Andaman earthquake, which caused permanent deformations recorded by continuously operating GPS networks in a region of unprecedented extent. Previous analysis of the static displacement fi eld focused on the heterogeneous distribution of moment release on the fault plane; our intention here is to investigate how much the presence of crustal heterogeneities trades off seismic source details. To this aim, we adopted a quite simple source model in modeling the event. The key feature of our analysis is the generation of a complex three dimensional spherical domain. More-over, we also made an accurate analysis concerning boundary conditions, which are crucial for FE simulations

Finite Element Modeling of the 2004 giant Sumatra Earthquake Postseismic Displacement Field

The 26 December 2004 Sumatra-Andaman earthquake is one of the largest earthquakes ever recorded since 1900. The earthquake resulted from complex slip on the fault where the oceanic portion of the Indian Plate slides under the Eurasian Plate, by the Indonesian Island of Sumatra. The particular features of the detected quasi-static displacement field has been previously attributed to the heterogeneous distribution of moment release on the fault plane. In the present work, we use a new computational FEM strategy to model the co- and postseismic displacement field associated with the Sumatra earthquake. For the first time we can study the joint effects of sphericity and 3D mechanical and rheological heterogeneities on the investigated observables. The comparison between our synthetic results and the available deformation data allows us to ascertain if also lateral heterogeneities in the physical properties of the medium could have played a role in assessing the deformation field