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Enhancing Transmission NVH Performance through Powertrain Control Integration with Active Braking System
No full textThis paper explores the potentiality of reducing noise and vibration of a vehicle transmission thanks to powertrain control integration with active braking. Due to external disturbances, coming from the driver, e.g. during tip-in / tip-out maneuvers, or from the road, e.g. crossing a speed bump or driving on a rough road, the torsional backlashes between transmission rotating components (gears, synchronizers, splines, CV joints), may lead to NVH issues known as clonk. This study initially focuses on the positive effect on transmission NVH performance of a concurrent application of a braking torque at the driving wheels and of an engine torque increase during these maneuvers; then a powertrain/brake integrated control strategy is proposed. The braking system is activated in advance with respect to the perturbation and it is deactivated immediately after to minimize losses. The powertrain control compensates for the added resistance and reestablishes the vehicle longitudinal performance according to driver's commands. The torsional preload created in the driveline is effective in preventing/reducing vibrations and associated noise. It is worth underlining that the proposed methodology can be directly applied to existing ABS/ESC units, composed of digital solenoid valves, and does not require additional hardware components. The effectiveness of this method has been experimentally validated by means of a Hardware In the Loop (HIL) test bench which includes a Dual Clutch (DCT) transmission and a hydraulic brake system with a customized ABS/ESC unit
Simulation of buck converters via numerical inverse Laplace transform
No full textThis paper focuses on the application of the theory of periodically switched circuits and systems to the steady-state and transient analysis of switching power converters. The proposed methodology is based on the derivation of an augmented companion network from topological inspection only. The above interpretation turns out to be time-invariant, thus allowing the frequency-domain analysis of the circuit by means of standard tools for the circuit analysis. Two alternative methods are used to compute the transient and the steady-state waveforms, namely the inverse discrete Fourier transform (IDFT) and the numerical inverse Laplace transform (NILT). The strength and the accuracy of the proposed approach is demonstrated on a buck converter via the prediction of its noisy absorbed current
METHODOS, PROCESSES FOR THE ENHANCEMENT OF CULTURAL HERITAGE: THE REHABILITATION OF THE MINOR ARCHITECTURE IN LIGURIA
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Symmetry-protected topological phases of one-dimensional interacting fermions with spin-charge separation
No full textThe low energy behavior of a huge variety of one-dimensional interacting spinful fermionic systems exhibits spin-charge separation, described in the continuum limit by two sine-Gordon models decoupled in the charge and spin channels. Interaction is known to induce, besides the gapless Luttinger liquid phase, eight possible gapped phases, among which are the Mott, Haldane, charge-/spin-density, and bond-ordered wave insulators, and the Luther Emery liquid. Here we prove that some of these physically distinct phases have nontrivial topological properties, notably the presence of degenerate protected edge modes with fractionalized charge/spin. Moreover, we show that the eight gapped phases are in one-to-one correspondence with the symmetry-protected topological (SPT) phases classified by group cohomology theory in the presence of particle-hole symmetry P. The latter result is also exploited to characterize SPT phases by measurable nonlocal order parameters which follow the system evolution to the quantum phase transition. The implications on the appearance of exotic orders in the class of microscopic Hubbard Hamiltonians, possibly without P symmetry at higher energies, are discussed
Las Torres landslide at Irazù volcano, Costa Rica: volume estimation and preferred direction of movement
No full textA study on slope instability has been made in the western sector of Irazú volcano, which comprises the definition of the geomorphological framework, the application of finite element technique known as shear resistance reduction, to analyze the stability of the sector defined as in process of destabilization and to stablish the volume of the potential landslide. Río Sucio Oeste Active Landslide (DARSO) was identified as the only active slide in the studied sector. In addition, it has been established that Retes Inactive Landslide (DIR) shows evidence of reactivation in the sector of its main escarpment. Moreover, it is not expected that DSPD landform presents a movement to the southwest in the future and the deformations shown by the model of a northwestward detachment become significant once the properties of shear strength are reduced by a factor of around 1.30; thus developing the collapse of the slope towards the northwest. If it is considered that the safety factor has a value of around 1.30, there must be a triggering factor for the landslide to develop. Finally, the volume of the landslide is estimated as 7 million cubic meters
