1,720,968 research outputs found
Ottimizzazione della disposizione di ponti estensimetrici sulle sale ferroviarie nella misura delle forze di contatto ruota-rotaia
No full textOttimizzazione numerica della disposizione di ponti estensimetrici sulle sale ferroviarie utilizzate nella misura delle forze di contatto ruota-rotaia
No full textLa misura delle azioni scambiate tra la ruota di un veicolo ferroviario e la rotaia durante la marcia è
normalmente eseguita attraverso il rilievo estensimetrico della deformazione delle ruote o dell’assile di
sale opportunamente strumentate.
A questo scopo sono state proposte varie configurazioni estensimetriche che si differenziano per la
disposizione dei ponti, la modalità di trattamento dei dati e le tecniche di taratura della catena di
misura.
L’intento del presente lavoro è quello di utilizzare un modello numerico della ruota, precedentemente sviluppato, per confrontare ed ottimizzare diverse configurazioni di ponti estensimetrici massimizzando le prestazioni in termini di rapporto segnale-rumore e riducendo la sensibilità ai fattori di disturbo e di deriva
Cento e più anni di ricerche di un problema complesso. La scuola tedesca.
No full textIn questo secondo articolo dedicato allo svio viene analizzato il contributo degli studiosi tedeschi, attivi durante la prima metà del novecento. Infine sono esposte considerazioni sull'attualità ed utilità di questo tipo di indagini e sulle prospettive di sviluppo
Evaluation of the effect of flange lubrication on wheel-rail contact forces
No full textThe paper illustrates a comparison between contact forces measured on a railway vehicle for Rome’s underground and those calculated with a Multi-Body Simulation code. It would have been quite difficult to obtain correct outputs from simulation without the availability of test results, since the measured coefficient of friction was substantially higher than what was desumed from the literature and the presence of flange lubricant proved to be essential for the dynamic behaviour of the vehicle. The simulations presented were thus carried out for different friction coefficients on flange and tread in order to illustrate the sensitivity of the model to these parameters
Life momentum at level crossing: human factor, road-rail safety policies, available technologies. A cross-sectorial challenge playing a rewarding role for the upgrade of safer mobility options
No full textThe relations between occurrences, misbehaviour and type of level crossing itself have been strictly correlated in a quantitative data analysis study (carried out in 2011) of the Italian Railway Investigation Body with the scientific collaboration of Academia.
So far, interaction between the available technologies, the road-railway infrastructure whereabouts, and the behavioural risk perceptive approach has been proved to be rewarding in order to identify the measures to adopt, according to the critical scenario, to manage safety both from the railway role side and from the mobility and road safety policies and strategies.
This paper offers reference data, graphs and schematic analytical approach of the criticalities raised up at level crossing (LC) when both accidents and incidents occurred, and from this set of results emerges the need of synergies and cross operative guidelines of interventions at LC spot. The UNECE, through the expert group in the WP1, should enhance safety at LC by leveraging knowledge, experience from road and railways sector, cooperating to offer parameters and guidelines valuable in a wider context so to make LC in line with the UN plan for sustainable life through a sustainable transport network development worldwide
Simulation and functional requirements of energy-efficient driving
No full textThe energy consumption of a train depends on characteristics of train and line, environmental conditions, comfort parameters, planned operation and different driving styles, that could cause relevant variation among different drivers operating the same
traction unit and timetable. The energy consumption calculation needs extended variable data bases and parameters to be kept under control. Driving style can play a rewarding role for the energy saving in itself and it is an important reference for the evaluation of technologies and operational measures aiming at
energy saving. Today energy meters on board the trains cover a lack of information about the real energy consumption of trains, therefore the authors are working on realistic and suitable
methodological approaches for data handling towards clearly defined objectives. In fact such data seem difficult to be useful if not well managed. The research activity is aiming to provide with a simplified approach for energy consumption evaluation useful to determine the more suitable driving style to save energy and respect the timetable in a specific line with a specific train. The proposed methodology is based on a simplified set of data: characteristics of the line usually provided by the infrastructure manager to operators and from them to their drivers, as well as the rolling stock characteristics usually provided by the supplier as design documentation. The methodology is based on simulations and is strictly related to the driver perspective with available documentation (timetable sheets and regulations). This paper describe the first results of the proposed simplified approach to determine the most suitable driving styles to save energy and respect the timetable constraints by line section and timetable structure. The assessment of strategies are based on analytical calculations and simulation of drivers behaviours on the Italian railway network
Lo svio. Cento e più anni di ricerche su un problema complesso. Gli inizi e la scuola francese
No full textPrimo articolo di una serie dedicata al
problema dello svio. Viene analizzata storicamente la vasta
letteratura tecnica su questo problema, la quale è stata
suddivisa in parti omogenee riflettenti i contributi di ricercatori
francesi, tedeschi, giapponesi e di gruppi internazionali.
Questo lavoro è dedicato agli autori francesi
POCHET, NADAL, MARIÈ e CHARTET e si conclude con una
prima proposta di evoluzione degli studi sulla prevenzione
dello svio, basata sui rischi statistici che lo caratterizzano
e sulla sua fenomenologia dinamica
On-board Measurement of Wheel/Rail Contact Forces for Research Purposes
No full textThis paper illustrates the current progress of research work dealing with the use of on-board force measurements to broaden understanding of interaction phenomena. For this purpose, experimental results from static bench tests and field tests with the innovative CML method are compared with those obtained from Finite Element Modelling (FEM) and Multi-Body Simulation (MBS). This also leads to indications for the proper use of MBS for vehicle dynamics calculations
Lo svio. Cento e più anni di un problema complesso. I deragliatori
No full textThe experimental researches on derailments made in Europe in the last century with the use of special vehicles are examined. The results qualitatively confirm the more advanced theories of Heumann and Chartet but they also pose new problems related to the track deformability and to the complexity of tribological phenomena involved in derailments. This requires the adoption of precautionary limits for H and Y/Q independent from theoretical models. These limits can be found in the technical legislation currently in force. A recent resumption of experimentation, based on the use of advanced computational and measurement technologies, produced enlightening results and on the one hand confirmed already known prolems and on the other hand highlighted unforeseen dynamic phenomena at high speeds
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