O galope nordestino diante do parque industrial: o projeto estético do Quinteto Armorial no Brasil moderno

Pós-graduação em História - FCHS

A simplified approach to determine aerodynamic damping of railway overheads

The railway overhead (or catenary) is the system of cables responsible for providing electric current to the train. This system has been reported as wind-sensitive (Scanlon et al., 2000), and particularly to the occurrence of galloping phenomena. Galloping phenomena of the railway overhead consists of undamped cable oscillations triggered by aerodynamic forces acting on the contact wire. As is well known, aerodynamic loads on the contact wire depends on the incident flow mean velocity and the angle of attack. The presence of embankments or hills modifies both vertical velocities profiles and angles of attack of the flow (Paiva et al., 2009). The presence of these cross-wind related oscillations can interfere with the safe operation of the railway service (Johnson, 1996). Therefore a correct modelling of the phenomena is required to avoid these unwanted oscillations.

Dynamic analysis using finite elements to calculate the critical wear section of the contact wire in suburban railway overhead conductor rails

The purpose of this study is to determine the critical wear levels of the contact wire of the catenary on metropolitan lines. The study has focussed on the zones of contact wire where localised wear is produced, normally associated with the appearance of electric arcs. To this end, a finite element model has been developed to study the dynamics of pantograph-catenary interaction. The model includes a zone of localised wear and a singularity in the contact wire in order to simulate the worst case scenario from the point of view of stresses. In order to consider the different stages in the wire wear process, different depths and widths of the localised wear zone were defined. The results of the dynamic simulations performed for each stage of wear let the area of the minimum resistant section of the contact wire be determined for which stresses are greater than the allowable stress. The maximum tensile stress reached in the contact wire shows a clear sensitivity to the size of the local wear zone, defined by its width and depth. In this way, if the wear measurements taken with an overhead line recording vehicle are analysed, it will be possible to calculate the potential breakage risk of the wire. A strong dependence of the tensile forces of the contact wire has also been observed. These results will allow priorities to be set for replacing the most critical sections of wire, thereby making maintenance much more efficient. The results obtained show that the wire replacement criteria currently borne in mind have turned out to be appropriate, although in some wear scenarios these criteria could be adjusted even more, and so prolong the life cycle of the contact wire.

Comparison of vibration and rolling noise emission of resilient and solid monobloc railway wheels in underground lines

Flat or worn wheels rolling on rough or corrugated tracks can provoke airborne noise and ground-borne vibration, which can be a serious concern for nearby neighbours of urban rail transit lines. Among the various treatments used to reduce vibration and noise, resilient wheels play an important role. In conventional resilient wheels, a slightly prestressed V­shaped rubber ring is mounted between the steel wheel centre and tyre. The elastic layer enhances rolling noise and vibration suppression, as well as impact reduction on the track. In this paper the effectiveness of resilient wheels in underground lines, in comparison to monobloc ones, is assessed. The analysed resilient wheel is able to carry greater loads than standard resilient wheels used for light vehicles. It also presents a greater radial resiliency and a higher axial stiffness than conventional V­wheels. The finite element method was used in this study. A quarter car model was defined, in which the wheelset was modelled as an elastic body. Several simulations were performed in order to assess the vibrational behaviour of elastic wheels, including modal, harmonic and random vibration analysis, the latter allowing the introduction of realistic vertical track irregularities, as well as the influence of the running speed. Due to numerical problems some simplifications were needed. Parametric variations were also performed, in which the sensitivity of the whole system to variations of rubber prestress and Poisson’s ratio of the elastic material was assessed.Results are presented in the frequency domain, showing a better performance of the resilient wheels for frequencies over 200 Hz. This result reveals the ability of the analyzed design to mitigate rolling noise, but not structural vibrations, which are primarily found in the lower frequency range.

Sensitivity analysis to assess the influence of the inertial properties of railway vehicle bodies on the vehicle’s dynamic behaviour

A sensitivity analysis has been performed to assess the influence of the inertial properties of railway vehicles on their dynamic behaviour. To do this, 216 dynamic simulations were performed modifying, one at a time, the masses, moments of inertia and heights of the centre of gravity of the carbody, the bogie and the wheelset. Three values were assigned to each parameter, corresponding to the percentiles 10, 50 and 90 of a data set stored in a database of railway vehicles. After processing the results of these simulations, the analyzed parameters were sorted by increasing influence. It was also found which of these parameters could be estimated with a lesser degree of accuracy for future simulations without appreciably affecting the simulation results. In general terms, it was concluded that the most sensitive inertial properties are the mass and the vertical moment of inertia, and the least sensitive ones the longitudinal and lateral moments of inertia.

A Novel Ground Fault Identification Method for 2 x 5 kV Railway Power Supply Systems

The location of ground faults in railway electric lines in 2 × 5 kV railway power supply systems is a difficult task. In both 1 × 25 kV and transmission power systems it is common practice to use distance protection relays to clear ground faults and localize their positions. However, in the particular case of this 2 × 25 kV system, due to the widespread use of autotransformers, the relation between the distance and the impedance seen by the distance protection relays is not linear and therefore the location is not accurate enough. This paper presents a simple and economical method to identify the subsection between autotransformers and the conductor (catenary or feeder) where the ground fault is happening. This method is based on the comparison of the angle between the current and the voltage of the positive terminal in each autotransformer. Consequently, after the identification of the subsection and the conductor with the ground defect, only the subsection where the ground fault is present will be quickly removed from service, with the minimum effect on rail traffic. This method has been validated through computer simulations and laboratory tests with positive results.

Railway surgeon.

Caption title.

Report to the President by the Emergency Board appointed February 4, 1950, by Executive order 10105, pursuant to Section 10 of the Railway Labor Act, as amended : to investigate and report in respect to a dispute between the Denver & Rio Grande Western Railroad Company, a carrier, and certain of its employees represented by the Brotherhood of Railroad Trainmen (NMB case A-3065), Denver, Colorado, February 28, 1950.

Signed: Robert G. Simmons, chairman, Robert O. Boyd, member, Harold R. Korey, member.

Report to the President by the Emergency Board created June 23, 1948 by Executive order 9971 pursuant to Section 10 of the Railway Labor Act : to investigate and report upon a dispute between the Grand Trunk Western Railroad Co., Chesapeake and Ohio Railway Co., Wabash Railroad and the Ann Arbor Railroad Co. and certain of its employees represented by the National Maritime Union of America, N.M.B. cases A-2801, A-2802, A-2803, A-2804, Detroit, Michigan, July 20, 1948.

Signed: Robert G. Simmons, chairman, Thomas F. Gallagher, member, Joseph L. Miller, member.

Report to the President by the Emergency Board appointed September 15, 1949, by Executive order 10078, pursuant to Section 10 of the Railway Labor Act, as amended : to investigate an unadjusted dispute between the Monongahela Connecting Railroad Company and certain of its employees represented by the Brotherhood of Railroad Trainmen, a labor organization (N.M.B. no. A-3220), Pittsburgh, Pa., October 7, 1949.

Signed: Harry H. Schwartz, chairman, Francis J. Robertson, member, Andrew Jackson, member.

Twenty years under the Railway labor act, amended, and the National Mediation Board, 1934-1954.

"The Railway labor act": p. 59-82.

Report to the President by the Emergency Board appointed April 10, 1948 pursuant to Section 10 of the Railway Labor Act, as amended : to investigate unadjusted disputes between the Pennsylvania Railroad Company and certain of its employees represented by the Brotherhood of Locomotive Firemen and Enginemen, Philadelphia, Pa. and New York, N.Y. June 9, 1948 (N.M.B. case A 2791).

"Respectively submitted. Andrew Jackson, Chairman, James H. Wolfe, Member, E. Wight Bakke, Member"--Page [ii].

Report to the President by the Emergency Board, created August 1, 1947 by Executive order 9880 pursuant to Section 10 of the Railway Labor Act : to investigate and report upon a dispute between the Brotherhood of Railroad Trainmen and River Terminal Railway Co. : (NMB case no. A-2542) : Cleveland, Ohio, August 20, 1947.

Signed on page ii: Frank M. Swacker, chairman, Hugh B. Fouke, member, Sidney St. F. Thaxter, member.

Report to the President by the Emergency Board created March 18, 1948 by Executive order 9936 pursuant to Section 10 of the Railway Labor Act : to investigate and report upon a dispute between the Terminal Railroad Association of St. Louis and certain of its employees represented by the Brotherhood of Locomotive Engineers, the Brotherhood of Locomotive Firemen and Enginemen and the Brotherhood of Railroad Trainmen : St. Louis, Missouri, April 7, 1948.

Signed: Frank M. Swacker, chairman, George Cheney, member, James H. Wolfe, member.

Report to the President by the Emergency Board appointed May 12, 1949 by Executive order 10056 pursuant to Section 10 of the Railway Labor Act, as amended : to investigate a dispute between the Union Railroad Company (Pittsburgh) and certain of its employees represented by the Brotherhood of Railroad Trainmen : (NMB case A-3083) : Pittsburgh, Pennsylvania, July 29, 1949.

Signed: Andrew Jackson, chairman, Leif Erickson, member, Elmer T. Bell, member.