Vibration of electrodes in operation strongly affects the efficiency of the electric arc furnace (EAF) fed by ac current during the steel smelting process. Therefore, an effective control of the ...structural dynamics through an active system is a current goal of the "intelligent manufacturing" approach. A vertical position control applied to each electrode allows keeping the arc length almost constant and reduces the effects of some electromechanical actions due to the mutual magnetic induction among the three electric phases. Nevertheless, control action needs for a detailed model of the whole system dynamic behavior. A new method for modeling the equipment behavior and somehow the process was implemented. A key issue was including into the model all the electromechanical coupling effects occurring in this system and suitably linking to the structural dynamics. Modeling activity was performed by resorting to the multibody dynamics and the finite-element method, while some analytical formulations were used to describe both the electric arc behavior and the control. A preliminary validation on a real plant was performed as far as the huge size of the system allowed and an assessment of the mechanical design of the EAF was completed.
Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, although direct observational evidence is still scarce and debated. Here we ...present Early Release Science JWST NIRSpec IFU observations of the
z
= 1.59 prototypical obscured Active Galactic Nucleus (AGN) XID2028: This target represents a unique test case for studying quasar feedback at the peak epoch of AGN-galaxy co-evolution because extensive multi-wavelength coverage is available and a massive and extended outflow is detected in the ionised and molecular components. With the unprecedented sensitivity and spatial resolution of the JWST, the NIRSpec dataset reveals a wealth of structures in the ionised gas kinematics and morphology that were previously hidden in the seeing-limited ground-based data. In particular, we find evidence of an interaction between the interstellar medium of the galaxy and the quasar-driven outflow and radio jet that produces an expanding bubble from which the fast and extended wind detected in previous observations emerges. The new observations confirm the complex interplay between the AGN jet, wind and the interstellar medium of the host galaxy, highlighting the role of low-luminosity radio jets in AGN feedback. They also clearly show the new window that NIRSpec opens for detailed studies of feedback at high redshift.
This paper deals with numerical prediction of the nonlinear dynamic behaviour of electromechanical continuous microsystems, in presence of large displacements. Finite Element Method (FEM) is applied, ...by following so-called 'sequential' approach, based on the solution in series of coupled electromechanical problem. In spite of tested approaches available in the literature, a 'non-incremental' method is developed to enhance the performances of numerical tools. In practice, for microelectrostatic beam actuators, the total voltage may be applied once, in only one step, instead of by small increments.Non-incremental approach is based on two features. A special non-incremental beam element is introduced to deal with so-called geometrical nonlinearity of microbeam, caused by large displacement. It allows computing the total displacement of a cantilever microbeam, by integrating local rotation and axial deformation of cross-section, by avoiding to refer to the assumption of small displacement. Proposed procedure includes a preliminary static nonlinear analysis, to find the equilibrium condition, then a computation of nodal voltages for the deformed shape and of electric load. Equations of motion are integrated in time, by Newmark's method, while at each step, Newton-Raphson approach finds the instantaneous equilibrium, by applying the total voltage, instead of a small incremental value.Results evidenced a fast convergence even for large initial deflection. Moreover, typical peculiarities of nonlinear dynamic system, like softening effect in frequency response and amplitude jumping are observed. The whole proposed approach is currently under experimental validation and improvement to include damping effects, to study the dynamic stability of the microsystem.
Since February 2020, the outbreak of COVID-19 in Italy has forced the health care system to undergo profound rearrangements in its services and facilities, especially in the worst-hit areas in ...Northern Italy. In this setting, inpatient and outpatient services had to rethink and reorganize their activities to meet the needs of patients during the "lockdown". The Italian Association of Myology developed a survey to estimate the impact of these changes on patients affected by neuromuscular disorders and on specialized neuromuscular centers during the acute phase of COVID-19 pandemic.
We developed an electronic survey that was sent to neuromuscular centers affiliated with the Italian Association of Myology, assessing changes in pharmacological therapies provision, outpatient clinical and instrumental services, support services (physiotherapy, nursing care, psychological support) and clinical trials.
40% of surveyed neuromuscular centers reported a reduction in outpatient visit and examinations (44.5% of centers in Northern regions; 25% of centers in Central regions; 50% of centers in Southern regions). Twenty-two% of centers postponed in-hospital administration of therapies for neuromuscular diseases (23.4% in Northern regions; 13.0% in Central regions; 20% in Southern regions). Diagnostic and support services (physiotherapy, nursing care, psychological support) were suspended in 57% of centers (66/43/44% in Northern, Central and Southern centers respectively) Overall, the most affected services were rehabilitative services and on-site outpatient visits, which were suspended in 93% of centers. Strategies adopted by neuromuscular centers to overcome these changes included maintaining urgent on-site visits, addressing patients to available services and promoting remote contact and telemedicine.
Overall, COVID-19 pandemic resulted in a significant disruption of clinical and support services for patients with neuromuscular diseases. Despite the efforts to provide telemedicine consults to patients, this option could be promoted and improved further. A close collaboration between the different neuromuscular centers and service providers as well as further implementation of telehealth platforms are necessary to ensure quality care to NMD patients in the near future and in case of recurrent pandemic waves.
Predicting dynamic behavior of nonlinear micromechatronic systems is rather difficult, because of the effects produced by electromechanical coupling, nonlinearities and microscale. This lecture is ...aimed to introduce basic methods for mechanical design of microelectromechanical systems (MEMs), by means of a test case consisting of an electrostatic microactuator, with few degrees of freedom. A model of the whole microsystem is built, by following a systematic approach, typical of structural mechatronics, dealing with formulation and solution of the equations of motion. Methods herewith presented are already extended to continuous microsystems, applied to numerical methods and implemented in some commercial and academic tools.
