Modelling and control of mechatronic and robotic systems

3noopenopenGasparetto A.; Seriani S.; Scalera L.Gasparetto, A.; Seriani, S.; Scalera, L

The best and brightest. Positive selection and brain drain in Italian internal migrations

During the last decade, the internal migration flows from Southern Italy to the central and northern regions of the country have become more significant. Unlike the past, these flows are characterised by a strong incidence of qualified workers with secondary or tertiary education. Also, even in this restricted set of workers, the most talented (the best and brightest) individuals are the ones showing the highest propensity to migrate. This paper applies a binary segmentation technique to a database of 10701 individuals graduated at Palermo and Naples universities between 2004 and 2007 in order to get groups with mostly differentiated attitudes to migrate. The evidence shows that variables driving segmentation (i.e. the most relevant variables in explaining the propensity to migrate) are the subject of study (who graduates in engineering and scientific disciplines is more mobile), the graduation mark (who gets higher marks is more likely to migrate) and the family social and cultural background. This strong positive self selection of migrants enhances the ability of internal migration to trigger considerable harmful effects on origin regions and jeopardises Southern Italy to suffer from heavy losses of human capital.internal migration; positive self selection of migrants

Cable-Based Robotic Crane (CBRC): Design and Implementation of Overhead Traveling Cranes Based on Variable Radius Drums

In this paper, we present a new family of overhead traveling cranes based on variable radius drums (VRDs), called cable-based robotic cranes (CBRCs). A VRD is characterized by the variation of the spool radius along its profile. This kind of device is used, in this context, for the development of a cable-robot, which can support and move a load through a planar working area with just two degrees of freedom. First we present the kinematic analysis and the synthesis of the geometry of a VRD profile. Then, the schema of a bidimensional horizontal moving mechanism, based on the VRD theory, and an experimental prototype of a three-dimensional CBRC are presented. The features of this wire-based overhead crane and an analysis of cables tensions are discussed. Finally, the performance of this mechanism is evaluated, demonstrating a deviation between the end-effector and the nominal planar surface of less than 1% throughout the whole working area

Development of n-DoF preloaded structures for impact mitigation in cobots

A core issue in collaborative robotics is that of impact mitigation, especially when collisions happen with operators. Passively compliant structures can be used as the frame of the cobot, although usually they are implemented by means of a single DoF. However, n-DoF preloaded structures offer a number of advantages, in terms of flexibility in designing their behavior. In this work we propose a comprehensive framework for classifying n-DoF preloaded structures, including 1-, 2-, and 3-dimensional arrays. Also, we study the implications of the peculiar behavior of these structures - which present sharp stiff-to-compliant transitions at design-determined load thresholds - on impact mitigation. To this regard, an analytical n-DoF dynamic model was developed and numerically implemented. A prototype of a 10-DoF structure was tested under static and impact loads, showing a very good agreement with the model. Future developments will see the application of n-DoF preloaded structures to impact-mitigation on cobots and in the field of mobile robots, as well as to the field of novel architected materials

NTMpy: An open source package for solving coupled parabolic differential equations in the framework of the three-temperature model

The NTMpy code package allows for simulating the one-dimensional thermal response of multilayer samples after optical excitation, as in a typical pump-probe experiment. Several Python routines are combined and optimized to solve coupled heat diffusion equations in one dimension, on arbitrary piecewise homogeneous material stacks, in the framework of the so-called three-temperature model. The energy source deposited in the material is modelled as a light pulse of arbitrary cross-section and temporal profile. A transfer matrix method enables the calculation of realistic light absorption in presence of scattering interfaces as in multilayer samples. The open source code is fully object-oriented to enable a user-friendly and intuitive interface for adjusting the physically relevant input parameters. Here, we describe the mathematical background of the code, we lay out the workflow, and we validate the functionality of our package by comparing it to commercial software, as well as to experimental transient reflectivity data recorded in a pump-probe experiment with femtosecond light pulses

NTMpy: An open source package for solving coupled parabolic differential equations in the framework of the three-temperature model

The NTMpy code package allows for simulating the one-dimensional thermal response of multilayer samples after optical excitation, as in a typical pump-probe experiment. Several Python routines are combined and optimized to solve coupled heat diffusion equations in one dimension, on arbitrary piecewise homogeneous material stacks, in the framework of the so-called three-temperature model. The energy source deposited in the material is modelled as a light pulse of arbitrary cross-section and temporal profile. A transfer matrix method enables the calculation of realistic light absorption in presence of scattering interfaces as in multilayer samples. The open source code is fully object-oriented to enable a user-friendly and intuitive interface for adjusting the physically relevant input parameters. Here, we describe the mathematical background of the code, we lay out the workflow, and we validate the functionality of our package by comparing it to commercial software, as well as to experimental transient reflectivity data recorded in a pump-probe experiment with femtosecond light pulses.Program summaryProgram title: NTMpy v.0.1.1CPC Library link to program files: https: //doi.org/10.17632/5czr76gmwr.1Developer's repository link: https://github.com/udcm-su/NTMpyCode Ocean capsule: https://codeocean.com/capsule/5661399Licensing provisions: MIT licenseProgramming language: PythonExternal routines: Python 3.5 or higher, numpy, matplotlib, bsplines, tqdmNature of problem: 1-dimensional coupled non linear partial differential equations; diffusion and relaxation dynamics formultiple systems and multiple layers.Solution method: Simulate the diffusion and relaxation dynamics of up to 3 coupled systems via an object oriented user interface. In order to approximate the solution and its derivatives in space B-Spline interpolation is used. The solution is developed in time via the Explicit Euler method.Additional comments including restrictions and unusual features: A routine to automatically select the ideal time step for stability of the algorithm is implemented. Routines for output of raw data in order to post process and pre- made visualization routines are implemented. (C) 2021 The Author(s). Published by Elsevier B.V

The best and brightest. Selezione positiva e brain drain nelle migrazioni interne italiane

During the last decade, the internal migration flows from Southern Italy to the central and northern regions of the country have become more significant. Unlike the past, these flows are characterised by a strong incidence of qualified workers with secondary or tertiary education. Also, even in this restricted set of workers, the most talented (the best and brightest) individuals are the ones showing the highest propensity to migrate. This paper applies a binary segmentation technique to a database of 10701 individuals graduated at Palermo and Naples universities between 2004 and 2007 in order to get groups with mostly differentiated attitudes to migrate. The evidence shows that variables driving segmentation (i.e. the most relevant variables in explaining the propensity to migrate) are the subject of study (who graduates in engineering and scientific disciplines is more mobile), the graduation mark (who gets higher marks is more likely to migrate) and the family social and cultural background. This strong positive self selection of migrants enhances the ability of internal migration to trigger considerable harmful effects on origin regions and jeopardises Southern Italy to suffer from heavy losses of human capital

The best and brightest. Selezione positiva e brain drain nelle migrazioni interne italiane

During the last decade, the internal migration flows from Southern Italy to the central and northern regions of the country have become more significant. Unlike the past, these flows are characterised by a strong incidence of qualified workers with secondary or tertiary education. Also, even in this restricted set of workers, the most talented (the best and brightest) individuals are the ones showing the highest propensity to migrate. This paper applies a binary segmentation technique to a database of 10701 individuals graduated at Palermo and Naples universities between 2004 and 2007 in order to get groups with mostly differentiated attitudes to migrate. The evidence shows that variables driving segmentation (i.e. the most relevant variables in explaining the propensity to migrate) are the subject of study (who graduates in engineering and scientific disciplines is more mobile), the graduation mark (who gets higher marks is more likely to migrate) and the family social and cultural background. This strong positive self selection of migrants enhances the ability of internal migration to trigger considerable harmful effects on origin regions and jeopardises Southern Italy to suffer from heavy losses of human capital

Analysis in k-space of Magnetization Dynamics Driven by Strong Terahertz Fields

Demagnetization in a thin film due to a terahertz pulse of magnetic field is investigated. Linearized LLG equation in the Fourier space to describe the magnetization dynamics is derived, and spin waves time evolution is studied. Finally, the demagnetization due to spin waves dynamics and recent experimental observations on similar magnetic system are compared. As a result of it, the marginal role of spin waves dynamics in loss of magnetization is established.Comment: 5 pages, 6 figure

An experimental setup to test dual-joystick directional responses to vibrotactile stimuli

In this paper we investigate the influence of the location of vibrotactile stimulation in triggering the response made using two handheld joysticks. In particular, we compare performance with stimuli delivered either using tactors placed on the palm or on the back of the hand and with attractive (move toward the vibration) or repulsive prompts (move away from the vibration). The experimental set-up comprised two joysticks and two gloves, each equipped with four pager motors along the cardinal directions. In different blocks, fifty-three volunteers were asked to move the joysticks as fast as possible either towards or away with respect to the direction specified by a set of vibrating motors. Results indicate that participants performed better with attractive prompts (i.e. responses were faster and with fewer errors in conditions where participants were asked to move the joysticks in the direction of the felt vibration) and that the stimulation delivered on the back of the hand from the gloves gives better results than the stimulation on the palm delivered by the joysticks. Finally, we analyse the laterality, the relation between correct responses and reaction times, the direction patterns for wrong responses and we perform an analysis on the Stimulus-Response Compatibility and on the training effect