Automobiles are becoming more and more complex as multiple control systems are integrated into the vehicle platform. This paper investigates the coordination of active rear steering (RWS) and torque ...vectoring (TV) - which is enabled by independent electric motors at the rear axle - in controlling vehicle lateral dynamics. The proposed controller aims at enhancing vehicle handling performance and stability while cornering. The coordination of the two actuators is achieved by weighting their contribution based on their impact on vehicle dynamics according to the working condition. The impact of each control system is assessed by means of phase portraits. These plots are a very powerful tool for analysing vehicle nonlinear dynamics as they readily display vehicle stability properties and map equilibrium point locations and movement to changing parameters and control inputs. Based on phase portrait analysis, a performance index is thus proposed, which weights more the control action (TV or RWS) capable of leading the vehicle at the nearest equilibrium point with the fastest rate. The controller performance is assessed through numerical simulations carried out using a nonlinear 14 dofs vehicle model. Results are compared with ones of the two controllers alone (RWS and TV) in different manoeuvers and adherence conditions.
Electric motors offer the possibility to control the braking torque in a more precise way than the hydraulic circuit. The applied torque is in fact measured and so it can be used to feedback the ...controller. Moreover, this information can be used to estimate the tyre-road friction coefficient, before potential friction is reached. The present paper proposes a novel ABS control strategy for electric vehicles with distributed motors. The controller is a six states machine that uses the information on applied braking torque provided by the electric motors. This information is of paramount importance to understand when the wheel reaches the peak of the braking force. Simulation results shows the benefits of the proposed strategy, comparing the results with state of the art acceleration-based controller.
Stability control systems applying differential braking to inner/outer tires are nowadays a standard for passenger car vehicles (ESP, DYC). These systems assume as controlled variables both the yaw ...rate (usually measured on board) and the sideslip angle. Unfortunately this latter quantity can directly be measured only through very expensive devices however unsuitable for ordinary vehicle implementation and thus it must be estimated. Several state observers eventually adapting the parameters of their reference vehicle models have been developed at the purpose. However sideslip angle estimation is still an open issue. In order to avoid problems concerned with reference model parameters identification/adaptation, a layered neural network approach is proposed in this paper to estimate the sideslip angle. Lateral acceleration, yaw rate, speed and steer angle which can be acquired by ordinary sensors are used as inputs. The design of the neural network and the definition of the manoeuvres constituting the training set have been gained by means of numerical simulations with a 7 d.o.f.s vehicle model. Performance and robustness of the implemented neural network have subsequently been verified by post-processing the experimental data acquired with an instrumented vehicle and referred to several handling manoeuvres (step-steer, power on, double lane change, etc.) performed on various road surfaces. Results generally show a good agreement between the estimated and the measured sideslip angle.
Potential environmental impacts of engineered nanoparticles (ENPs) can be understood taking into consideration phytotoxicity. We reported on the effects of ionic (FeCl3), micro- and nano-sized ...zerovalent iron (nZVI) about the development of three macrophytes: Lepidium sativum, Sinapis alba and Sorghum saccharatum. Four toxicity indicators (seed germination, seedling elongation, germination index and biomass) were assessed following exposure to each iron concentration interval: 1.29–1570mg/L (FeCl3), 1.71–10.78mg/L (micro-sized iron) and 4.81–33,560mg/L (nano-iron). Exposure effects were also observed by optical and transmission electron microscopy. Results showed that no significant phytotoxicity effects could be detected for both micro- and nano-sized zerovalent irons, including field nanoremediation concentrations. Biostimulation effects such as an increased seedling length and biomass production were detected at the highest exposure concentrations. Ionic iron showed slight toxicity effects only at 1570mg/L and, therefore, no median effect concentrations were determined. By microscopy, ENPs were not found in palisade cells or xylem. Apparently, aggregates of nZVI were found inside S. alba and S. saccharatum, although false positives during sample preparation cannot be excluded. Macroscopically, black spots and coatings were detected on roots of all species especially at the most concentrated treatments.
•Nanoremediation activities use nano-zerovalent iron (nZVI).•Knowledge of nZVI effects on macrophytes are still scarce.•Standard phytotoxicity tests (72h exposure) showed no adverse effects of nZVI.•Micro-sized iron showed no significantly different effects from nZVI.•Apparent uptake of ZVI detected by microscopy.
Preserving cultural heritage against earthquake and ambient vibrations can be an attractive topic in the field of vibration control. This paper proposes a passive vibration isolator methodology based ...on inerters for improving the performance of the isolation system of the famous statue of Michelangelo Buonarroti Pietà Rondanini. More specifically, a five-degree-of-freedom (5DOF) model of the statue and the anti-seismic and anti-vibration base is presented and experimentally validated. The parameters of this model are tuned according to the experimental tests performed on the assembly of the isolator and the structure. Then, the developed model is used to investigate the impact of actuation devices such as tuned mass-damper (TMD) and tuned mass-damper-inerter (TMDI) in vibration reduction of the structure. The effect of implementation of TMDI on the 5DOF model is shown based on physical limitations of the system parameters. Simulation results are provided to illustrate effectiveness of the passive element of TMDI in reduction of the vibration transmitted to the statue in vertical direction. Moreover, the optimal design parameters of the passive system such as frequency and damping coefficient will be calculated using two different performance indexes. The obtained optimal parameters have been evaluated by using two different optimization algorithms: the sequential quadratic programming method and the Firefly algorithm. The results prove significant reduction in the transmitted vibration to the structure in the presence of the proposed tuned TMDI, without imposing a large amount of mass or modification to the structure of the isolator.
Owing to the increasing development of nanotechnology, there is a need to assess how engineered nanomaterials can interact with living cells. The main purpose of the present study was to assess ...whether metal cobalt nanoparticles (CoNP 100–500 nm) are genotoxic compared to cobalt ions (Co2+). Uptake experiments were carried out by incubating peripheral blood leukocytes (PBLs) with 57Co2+ (added to stable Co2+ 10−2 M to obtain concentrations in the range of 10−5 to 10−4 M) or with 60CoNP for 24 and 48 h. Whereas intracellular Co2+ showed slight or no variations over the baseline levels, CoNP were taken up efficiently leading to intracellular CoNP concentrations of 485 ± 106.1 and 970 ± 99 fg per cell after 24 and 48 h, respectively. The genotoxicity end points considered in this study were the frequency of binucleated micronucleated (BNMN) cells and the percentage of tail DNA (% Tail DNA) fragmentation by means of the comet assay. Genotoxic effects were evaluated by incubating PBLs of three healthy donors with subtoxic concentrations (10−5 to 8 × 10−5M) of Co2+ in the form of cobalt chloride, CoNP and ‘washed’ CoNP, the latter to exclude any interference by Co2+. On a group basis, Co2+ induced a clear trend in the increase of the BNMN frequency, whereas CoNP showed only minor changes. Moreover, we observed a high variability among donors in the induction of micronuclei. The comet assay showed a statistically significant dose-related increase in % Tail DNA for CoNP (P < 0,001), whereas Co2+ did not induce significant changes over control values. These findings suggest that nanosized Co can be internalized by human leukocytes and can interact with DNA leading to the observed genotoxic effects, which are, however, modulated both by donor's characteristics and/or by Co2+ release.
In the recent years, rollover has become an important safety issue for a large class of vehicles. Even though rollovers constitute a small percentage of all accidents, they have unproportionally ...large contribution to severe and fatal injuries. Under this point of view, rollover of heavy vehicles is particularly critical being associated with large traffic disruption, economic loss and risks connected to the transported goods. One of the main causes for heavy vehicles rollover is recognised to be cross wind. In order to determine which parameters (geometry and vehicle type, infrastructure scenario, turbulence conditions, etc.) most affect the aerodynamic loads acting on heavy vehicles, a comprehensive experimental campaign has been carried out in the Politecnico di Milano wind tunnel. The overall activity is presented in 2 papers. In this first paper attention is focused on a high-sided lorry in flat ground scenario. Mean aerodynamic forces and moments have been measured by means of a six-components dynamometric balance for different yaw angles and turbulence conditions. Moreover, in order to gain an insight of the flow pattern around the vehicle, pressure distribution on the vehicle surface has been measured. Finally, the vehicle aerodynamic admittance function has been assessed, for high turbulence conditions, to investigate the unsteady force/moment component. The second paper deals with the effect of infrastructure scenario (flat ground, embankment, double and single viaduct), of position (vehicle placed upwind or downwind) and of vehicle geometry/type (high-sided lorry with and without a trailed unit, tractor-semitrailer combination and tank truck) on the aerodynamic forces and moments, including both steady and unsteady components.
► Wind tunnel tests were performed on different heavy-road vehicles in different test conditions. ► Effects of scenario, vehicle and turbulence on force and pressure coefficients were studied. ► Effect of the vehicle geometry on the unsteady aerodynamic force component was analysed.
Reducing derailments of freight trains is of utter importance for improving railway transportation since derailments lead to large service disruption, economic losses and risk related to transported ...goods. The present paper studies low-speed (below 30 km/h) derailment of freight trains, performing experimental full-scale tests, using an instrumented wagon equipped with a commercial derailment detector. Specifically, the dynamics of a freight wagon during wheel-climb derailment and the motion with one axle derailed are investigated. During the tests, accelerations were measured at the bogie and at the carbody. Moreover, the intervention of the derailment detector was monitored to assess possible causes of false tripping or miss-detections. Two loading conditions were analysed: empty and loaded wagon. Main achievements may be summarised as follows: (1) the activation of the derailment detector is always triggered by impacts between the axle-box and the rail; (2) if the wagon is empty, vibrations induced by a derailed axle over the sleepers strongly depend on vehicle speed and they may not trigger the derailment detector in the range 15-25 km/h; (3) derailment detectors must be installed at both ends of each wagon. This information may be used to develop derailment detection algorithms integrated into electric control units with computing capabilities..
The sensitivity of heavy road vehicle aerodynamic coefficients to different testing parameters (scenario, vehicle type and turbulence intensity) is experimentally evaluated in this paper through wind ...tunnel experiments. The first part of the paper has investigated the aerodynamic loads (both stationary and non-stationary) acting on a high-sided lorry (VAN) in a flat ground scenario. The mean aerodynamic coefficients, the flow pattern around the vehicle and the aerodynamic admittance function have been assessed and compared for different wind turbulence conditions (boundary layer simulations). The present paper instead investigates the influence of the infrastructure scenario (flat ground, embankment, single and double viaduct), of the exposition (upwind or downwind) and of a trailed unit on the aerodynamic loads acting on the vehicle. Moreover, the mean aerodynamic coefficients and the aerodynamic admittance function of the high-sided lorry considered in the first part are compared with the ones of other heavy vehicles (tank truck, tractor–semitrailer combination and tractor–trailer combination) to assess the influence of the vehicle geometry.
► An extensive wind tunnel experimental campaign has been performed on a heavy-vehicle model (VAN). ► Effects of yaw angle and boundary layer on force and pressure coefficients were investigated. ► Main effects due to yaw angle were found at the windward upper edge. ► Main effects due to boundary layer were found at high yaw angles, especially on side and lift force.
Patients with chronic pain disorders often show somatosensory disturbances that are considered to be functional. This paper aims at a more precise clinical description and at a documentation of ...functional neuroimaging correlates of this phenomenon. We examined 30 consecutive patients with unilaterally accentuated chronic pain not explained by persistent peripheral tissue damage and ipsilateral somatosensory disturbances including upper and lower extremities and trunk. The patients were assessed clinically and with conventional brain CT or MRI scan. In the last 11 patients functional neuroimaging was carried out (18-fluordeoxyglucose positron emission tomography=FDG-PET). Depressive symptoms were assessed with the Hamilton depression scale (HAMD-17) and pain intensity was rated with a visual analogue scale for pain (VAS). All patients suffered from mild to moderate depressive symptoms. All patients had experienced a prolonged antecedent phase of severe emotional distress; most of them remembered a "trigger episode of somatic pain" on the affected side. Somatosensory deficits were a replicable hyposensitivity to touch and heat perception of nondermatomal distribution. Conventional imaging procedures (brain CT or MRI scans) showed no structural changes. However, in 11 patients functional imaging with FDG-PET showed a significant hypometabolic pattern of changes in cortical and subcortical areas, mainly in the post-central gyrus, posterior insula, putamen, and anterior cingulate cortex. In summary, pain-related nondermatomal somatosensory deficits (NDSDs) are a phenomenon involving biological as well as psychosocial factors with replicable neuroperceptive clinical findings and a complex neurodysfunctional pattern in the FDG-PET.
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