O cultivo da beterraba para produção de álcool ou forragem na região sul do Brasil.

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Experimental analysis of train slipstream in confined spaces

The train slipstream, i.e. the air velocities induced by the train, is one of the most important aerodynamic effects connected to railway vehicles because it has a direct impact on the safety of passengers on the platform and track workers along the railway line. In recent years, a lot of studies were performed to understand the development of this phenomenon in the open field and specific EU standards, the EN 14067-4 and the TSI (Technical Specifications for Interoperability) were issued. On the other hand, only few studies have been carried out to analyze the train passages in confined spaces (as tunnels, line sections with acoustic barriers, etc.), even if the first results of these analyses have shown that the confinement of the air causes more severe conditions regarding the speed of the air flow. This work aims at studying, through a full-scale experimental campaign, the effects of the flow confinement on the air speed caused by the train passage. In particular, the effects of different parameters, linked to the train i.e. the train type and length, the train speed and the measurement position, and linked to the infrastructure i.e. variations in the local infrastructure geometry, were analyzed

Numerical and Experimental Analysis of the Pressure Signature for different High-Speed Trains

This paper describes a procedure for the validation of numerical codes able to reproduce the pressures in tunnel due to the passage of trains. In the first step, the parameters of the numerical code are set by matching the train-tunnel pressure signature measured during a single-passage of different types of train within the tunnel and in the second step, without changing the parameters, the crossing of two trains is simulated. Within the paper, the methodology is applied to the numerical mono-dimensional code DB-Tunnel while the experimental data are those collected during an experimental research programme carried out in the tunnel La Fornace, on the Italian high-speed railway from Roma to Firenze. The accuracy of the numerical code estimation is evaluated in terms of the maximum pressure generated in the tunnel by the train passing/crossing because this is the key parameter, according to the TSI standard for railway infrastructures

Simplified estimation of the train resistance parameters: full scale experimental tests and analysis

A CEN standard (EN 14067-4, 2005) describes the methodologies for the assessment of the running resistance of railway vehicles starting from full-scale test measurements. According to this standard, the speed dependent terms of the equation of Davis [1] have to be determined by means of coasting tests. In this paper, a new method to estimate the running resistance coefficients from a full-scale coasting test is proposed and compared with the two methods proposed in the CEN standard (the regression method and the speed history identification method). The main advantage of this new method is that it does not require the railway line characteristics to be known and it will be shown that the new method is able to evaluate the coefficients with an accuracy equivalent to that of the other methods considered

Controlled Lactonization of o-Coumaric Esters Mediated by Supramolecular Gels

Fragrances are volatile organic compounds widely used in our daily life. Unfortunately, the high volatility required to reach human receptors reduces their persistency in the air. To contrast this effect, several strategies may be used. Among them, we present here the combination of two techniques: the microencapsulation in supramolecular gels and the use of profragrances. We report a study on the controlled lactonization of four esters derived from o-coumaric acid. The ester lactonization spontaneously occurs after exposure to solar light, releasing coumarin and the corresponding alcohol. To determine the rate of fragrance release, we compared the reaction in solution and in a supramolecular gel and we demonstrated that the lactonization reaction always occurs slower in the gel. We also studied the more suitable gel for this aim, by comparing the properties of two supramolecular gels obtained with the gelator Boc-L-DOPA(Bn)(2)-OH in a 1:1 ethanol/water mixture in different gelator concentration (0.2% and 1% w/v). The gel prepared with 1% w/v gelator concentration is stronger and less transparent than the other and was used for the profragrances encapsulation. In any case, we obtained a significative reduction of lactonization reaction in gel, compared with the same reaction in solution

Full scale experimental tests to evaluate the train slipstream in tunnels

The train slipstream, i.e. the air velocity induced by the train, is one of the most important aerodynamic effects connected to railway vehicles because it has a direct impact on the safety of passengers on the platform and track workers along the railway line. In recent years, a lot of studies were performed to understand the development of this phenomenon in open field, and specific EU standards, the EN 14067–4 and the TSI were issued. Instead, only few studies have been carried out to analyse the train slipstream in confined spaces (as tunnels, line sections with acoustic barriers, etc.), even though the first results of these analyses have shown that the confinement of the air causes more severe conditions regarding the speed of the air flow. This work aims at studying, through a fullscale experimental campaign, the effects on the air flow speed caused by the train passage. The effects of different train parameters (i.e. train type and length, etc.) and infrastructure parameters (i.e. geometry variations) were analysed. Lastly, the results of a specific test considering the presence of a stationary train inside the tunnel while another train is passing are described, to simulate scenarios of ordinary railway traffic

Evaluation of the Aerodynamic Effect of a Smooth Rounded Roof on Crosswind Stability of a Train by Wind Tunnel Tests

The advent of high-speed trains led to new issues and constraints for railway network manufacturers and operators. This is the case of crosswind effect, that occurs when train is running in strong wind conditions. The combination of train speed and wind speed generates a relative flow that affects the train stability. Wind tunnel tests on still railway vehicles (relative wind-train velocity in coincidence with absolute wind velocity) are mandatory according to Technical Specification for Interoperability (TSI) to ensure high-speed train safety. However, issues related to the correct evaluation of the full-scale aerodynamic behaviour of the trains can arise. In the present work, aerodynamic force and pressure coefficients measured in wind tunnel tests on a scaled model of ETR1000 high-speed train on single track ballast and rails are presented. The tests were performed in the GVPM wind tunnel of Politecnico di Milano. Results show that different flow behaviours can occur at high yaw angles when the train behaves like a bluff body depending on wind speed used during the test

A study of the influence of aerodynamic loads on the forces exchanged in a twistlock corner casting connection of flat-wagons

In this paper cross-wind effects on freight wagons are studied. A mathematical model of a freight train made up of a flat-car and one or two containers has been built defining the dynamical characteristics of the connection (twistlock-corner casting). Wind tunnel tests on a scaled model are then used to define the aerodynamic coefficients of the wagon, both in loaded and unloaded conditions, considering different trainset layouts. Wind forces are finally applied separately to the container and the flat-car in order to define the CWC of the wagon and to verify the maximum forces exchanged through the twistlock-corner casting connection. The results of the analysis showed that severe conditions with respect to the risk of rollover can be found as a result of a succession of empty and loaded wagons