An Engel condition for orderable groups

Let m,n be positive integers, v a multilinear commutator word and w=v^m. We prove that if G is an orderable group in which all w-values are n-Engel, then the verbal subgroup v(G) is locally nilpotent. We also show that in the particular case where v=x the group G is nilpotent (rather than merely locally nilpotent)

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

Steering Behavior of an Articulated Amphibious All-Terrain Tracked Vehicle

This paper presents a study related to an Articulated Amphibious All-Terrain Tracked Vehicle (ATV) characterized by a modular architecture. The ATV is composed by two modules: The first one hosts mainly the vehicle engine and powertrain components, meanwhile the second one can be used for goods transportation, personnel carrier, crane and so on. The engine torque is transmitted to the front axle sprocket wheel of each module and finally distributed on the ground through a track mechanism. The two modules are connected through a multiaxial joint designed to guarantee four relative degrees of freedom. To steer the ATV, an Electro Hydraulic Power System (EHPS) is adopted, thus letting the vehicle steerable on any kind of terrain without a differential tracks speed. The paper aims to analyze the steady-state lateral behavior of the ATV on a flat road, through a non-linear mathematical vehicle model built in Matlab/Simulink environment. The model describes the vehicle main planar motion and the interaction between the two modules through the application of a hydraulic steering torque. The model simulates steady-state handling maneuvers in Matlab/Simulink. Two scenarios are considered: One with the application of an open-loop hydraulic steering torque without any vehicle feedback; the second one with a closed-loop steering torque actuation based on the relative angle between the two modules (hitch angle). Finally, the influence of the ATV longitudinal speed on vehicle lateral characteristics is also presented

A Methodology for Parameter Estimation of Nonlinear Single Track Models from Multibody Full Vehicle Simulation

In vehicle dynamics, simple and fast vehicle models are required, especially in the framework of real-time simulations and autonomous driving software. Therefore, a trade-off between accuracy and simulation speed must be pursued by selecting the appropriate level of detail and the corresponding simplifying assumptions based on the specific purpose of the simulation. The aim of this study is to develop a methodology for map and parameter estimation from multibody simulation results, to be used for simplified vehicle modelling focused on handling performance. In this paper, maneuvers, algorithms and results of the parameter estimation are reported, together with their integration in single track models with increasing complexity and fidelity. The agreement between the multibody model, used as reference, and four single track models is analyzed and discussed through the evaluation of the correlation index. The good match between the models validates the adopted simulation methodology both during steady-state and during transient maneuvers. In a similar way, this method could be applied to experimental data gathered from a real instrumented car rather than from a multibody model

Energy Management Strategy for Hybrid Multimode Powertrains: Influence of Inertial Properties and Road Inclination

Multimode hybrid powertrains have captured the attention of automotive OEMs for their flexible nature and ability to provide better and optimized efficiency levels. However, the presence of multiple actuators, with different efficiency and dynamic characteristics, increases the problem complexity for minimizing the overall power losses in each powertrain operating condition. The paper aims at providing a methodology to select the powertrain mode and set the reference torques and angular speeds for each actuator, based on the power-weighted efficiency concept. The power-weighted efficiency is formulated to normalize the efficiency contribution from each power source and to include the inertial properties of the powertrain components as well as the vehicle motion resistance forces. The approach, valid for a wide category of multimode powertrain architectures, is then applied to the specific case of a two-mode hybrid system where the engagement of one of the two clutches enables an Input Split or Compound Split operative mode. The simulation results obtained with the procedure prove to be promising in avoiding excessive accelerations, drift of powertrain components, and in managing the power flow for uphill and downhill vehicle conditions

Articulated Steering Control for an All-Terrain Tracked Vehicle

The objective of this study is to analyse and control the cornering behaviour of an Articulated All-Terrain Tracked Vehicle (ATV). The ATV is characterized by two units connected through a mechanical multiaxial joint designed to overcome extreme longitudinal and side slopes. The hydraulic actuation of the joint enables an articulated steering feature thus avoiding any thrusts adjustment as it happens for skid-steering vehicles. A direct curvature controller is presented for analysing the steady-state ATV behaviours through a nonlinear model. Furthermore, a hitch angle controller is introduced to overcome the necessity of a curvature feedback measurement. The methodology is verified by simulating typical manoeuvres adopted for evaluating vehicle handling performance

Torsional Dynamic Performance of a Transmission Test Bench: An Investigation on the Effect of Motors Controllers Parameters

Besides in-vehicle testing, automotive powertrains and their subsystems are extensively studied and verified, in the different development phases, through dedicated test benches having various mechanical layouts according to the specific target. The torsional load is typically applied to the transmission by electric motors connected at both ends of the driveline. The electric motors drives allow speed and torque closed-loop control so that the desired combination of speed and torque can be imposed over time during the experiment. The parameters of such controllers therefore play a crucial role in the torsional dynamic behavior of the bench and therefore must be carefully selected and tuned to achieve optimal reference tracking and disturbance rejection performance. This paper aims at proposing a model-based sensitivity analysis of the PID controllers parameters starting from an experimentally validated torsional model of a Dual Clutch Transmission test rig. The methodology here proposed also contributes to achieving the Sustainable Development Goal 11 promoted by ONU

THE MANAGEMENT AND CAPITALIZATION OF THE LANDSCAPING POTENTIAL OF THE CRUCII SQUARE FROM TIMISOARA CITY

The Crucii Square is situated in the Elisabetin district in the city of Timisoara, in a residential area. According to a map from 1849, the current Crucii Square is situated on the very line of the building injunction circle around the fortress of Timisoara. The square name originates from an old cross which was preserved until today. Taking into the age of the oldest trees, the square was set as a green space after 1920. The current landscaping consists in tracing and slabbing the allies and building a new hero monument, also dates from after 1920. The square’s surface is of 6255mp. In the present paper we carried out an estimate of the green space and determined the current vegetation state, since green cadastre is the only way to determine the real state of green spaces belonging to a city’s patrimony, including parks and squares as well as the entire street vegetation (Ciupa et al., 2005). The paper‘s character is thus that of a vegetation fund inventory, as well as organisational design based on ecologic and landscaping criteria. The paper also comprises a square landscaping proposal, highlighting the site’s historic character and the high vegetation value