337 research outputs found
A model for a flywheel automatic assistedmanual transmission
This paper is focused on the model and dynamical analysis of a flywheel assisted transmis- sion aiming at reducing the torque gap during gear shift manoeuvres. A completely passive device, consisting of a planetary gear set mounting a flywheel on the sun gear shaft, allows to continuously connect the engine to the load shaft. Depending on the operating condi- tions, it can either absorb energy from the engine or deliver the previously stored kinetic energy to the wheels when the clutch is disengaged, thus allowing better vehicle performances and/or ride comfort through a suitable coordinated control of engine and clutc
Experimental device to identify friction levels for airport applications
This paper presents an experimental device aimed at
identifying different road friction levels; it has been designed
at the Politecnico di Torino as part of the research
program AWIS (Airport Weather Information
System: study and realisation of a system for the prediction,
monitoring and management of meteorological
winter emergencies in airports) funded by Regione
Piemonte
On the Power-Weighted Efficiency of Multimode Powertrains: A Case Study on a Two-Mode Hybrid System
Multimode powertrains represent one of the most versatile solutions for hybrid electric vehicles where multiple power sources are integrated with aim of improving fuel economy and reducing pollutants emission in every operating condition. Some hybrid powertrain designs feature multiple planetary gear sets whose components can be directly driven by the powertrain actuators (electric motor or thermal engine) or can be connected through clutches and brakes. The advantages due to the availability of multiple modes are mitigated by the increase of production costs and complexity because of the higher number of components required if compared with the single mode solutions. A numerical methodology is adapted from the literature to analyze, categorize, and compare each distinct working configuration. The energy consumption of each powertrain configuration is then evaluated through the power-weighted efficiency concept whose formulation normalize the contribution from each power source. This paper aims at extending the methodology to investigate the operating range for each powertrain configuration to always achieve the maximum efficiency. The methodology is then applied to the realistic case study of the EVT 2-Mode Hybrid System
BPS wilson loops in generic conformal N = 2 SU(N) SYM theories
We consider the 1/2 BPS circular Wilson loop in a generic N = 2 SU(N) SYM theory with conformal matter content. We study its vacuum expectation value, both at finite N and in the large-N limit, using the interacting matrix model provided by localization results. We single out some families of theories for which the Wilson loop vacuum expectation values approaches the N = 4 result in the large-N limit, in agreement with the fact that they possess a simple holographic dual. At finite N and in the generic case, we explicitly compare the matrix model result with the field-theory perturbative expansion up to order g^8 for the terms proportional to the Riemann value zeta(5), finding perfect agreement. Organizing the Feynman diagrams as suggested by the structure of the matrix model turns out to be very convenient for this computation
Integrated correlators with a Wilson line in SYM
In the context of integrated correlators in SYM, we study the
2-point functions of local operators with a superconformal line defect.
Starting from the mass-deformed theory in presence of a
-BPS Wilson line, we exploit the residual superconformal symmetry
after the defect insertion, and show that the massive deformation corresponds
to integrated insertions of the superconformal primaries belonging to the
stress tensor multiplet with a specific integration measure which is explicitly
derived after enforcing the superconformal Ward identities. Finally, we show
how the Wilson line integrated correlator can be computed by the
Wilson loop vacuum expectation value on a 4-sphere in terms
of a matrix model using supersymmetric localization. In particular, we
reformulate previous matrix model computations by making use of recursion
relations and Bessel kernels, providing a direct link with more general
localization computations in theories.Comment: 34 pages, 1 figur
Adaptive Equivalent Consumption Minimization Strategy with Rule-based Gear Selection for the Energy Management of Hybrid Electric Vehicles Equipped with Dual Clutch Transmissions
Based on observations of the behaviour of the optimal solution to the problem of energy management for plug-in hybrid electric vehicles, a novel real-time Energy Management Strategy (EMS) is proposed. In particular, dynamic programming results are used to derive a set of rules aiming at reproducing the optimal gearshift schedule in electric mode while the Adaptive Equivalent Consumption Minimization Strategy (A-ECMS) is employed to decide the powertrain operating mode and the current gear when power from the internal combustion engine is needed. In terms of total fuel consumption, simulations show that the proposed approach yields results that are close to the optimal solution and also outperforms those of the A-ECMS, a well-known EMS. One of the main aspects that differentiates the strategy here proposed from previous works is the introduction of a model to use physical considerations to estimate the energy consumption during gearshifts in dual-clutch transmissions. This, together with a series of properly tuned fuel penalties allows the controller to yield results in which there is no gear hunting behaviour
Drivability analysis of through-the-road-parallel hybrid vehicles
In the last decade, Hybrid Electric Vehicles (HEVs) have spread worldwide due to their capability to reduce fuel consumption. Several studies focused on the optimisation of the energy management system of hybrid vehicles are available in literature, whilst there are few articles dealing with the drivability and the dynamics of these new powertrain systems. In this paper a ‘Through-the-Road-Parallel HEV' is analysed. This architecture is composed of an internal combustion engine mounted on the front axle and an electric motor powering the rear one. These two powertrains are not directly connected to each other, as the parallel configuration is implemented through the road-tyre force interaction. The main purpose of this paper is the drivability analysis of this layout of HEVs, using linearised mathematical models in both time (i.e. vehicle response during tip-in tests) and frequency domain (i.e. frequency response functions), considering the effect of the engaged gear ratio. The differences from a traditional Front-Wheel-Drive (FWD) configuration are subsequently highlighted. Furthermore, the authors compare different linearised dynamic models, with an increasing number of degrees of freedom, in order to assess which model represents the best compromise between complexity and quality of the results. Finally, a sensitivity analysis of the influence of the torque distribution between the front (thermal) and rear (electric) axles on vehicle drivability is carried out and presented in detai
Emitted radiation and geometry
In conformal N = 2 Super Yang-Mills theory, the energy emitted by an accelerated heavy particle is computed by the one-point function of the stress tensor operator in the presence of a Wilson line. In this paper, we consider the theory on the ellipsoid and we prove a conjectured relation between the stress tensor one-point function and the firrst order expansion of the Wilson loop expectation value in the squashing parameter. To do this, we analyze the behavior of the Wilson loop for a small deformation of the background geometry and, at firrst order in the deformation, we fix the kinematics using defect CFT constraints. In the final part of the paper, we analyze the consequences of our results for the weak coupling perturbative expansion. In particular, comparing the weakly coupled matrix model with the ordinary Feynman diagram expansion, we find a natural transcendentality driven organization for the latter
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