Lateral guidance control using information of preceding wheel pairs

The proceeding enhancement of sensor technology, data processing and communication opens a broad field to improve the dynamics of railway vehicles by controlled systems targeting e.g. passenger comfort and wear reduction. In terms of an integrated control structure, information of leading bogies can be used for an advanced control of the trailing ones, like it is recently applied in tilting trains. Such a approach has not yet been investigated for the lateral guidance of driven independently rotating wheels (DIRW). To evaluate the potential of a control using preview information, a integrated control structure is introduced in this work. The control is based on the concept of feedback linearization and considers characteristics of track trajectory and irregularity, which are obtained at a leading wheel pair. The control performance is optimized with the help of software-in-the-loop simulations and the results show a significant improvement of the running dynamics

Transcranial Direct Current Stimulation (tDCS) for Depression during Pregnancy: Scientific Evidence and What Is Being Said in the Media - A Systematic Review

Major depression is the most frequent morbidity in pregnancy. The first-line therapies, psychopharmacologic treatment and psychotherapy, are either insufficient or may cause severe or teratogenic adverse events. As a result of its local limitation to the patient's brain, transcranial direct current stimulation (tDCS) could potentially be an ideal treatment for pregnant women with depression. A literature search was conducted in medical databases, globally published newspapers, search engines, and clinical trial registers to collect all articles on tDCS for the treatment of depression during pregnancy. The aim of this review was to investigate the scientific evidence of tDCS use for depression during pregnancy and to compare these results with the textual and emotional perception in the media as interventions during pregnancy are under particular surveillance. We detected 13 medical articles dealing with tDCS for depression in pregnancy. Overall, the scientific evidence as well as articles in the media for tDCS in pregnancy are sparse, but promising. Further studies are required in this specifically vulnerable population of pregnant women to generate evidence. It is likely that public interest will increase when the results of a pilot study in Canada are published

Derailment risk and dynamics of railway vehicles in curved tracks: Analysis of the effect of failed fasteners

[EN] The effect of the fastener s failure in a railway track on the dynamic forces produced in the wheel-rail contact is studied using the simulation software VAMPIRE to assess the derailment risk of two different vehicles in two curves with distinct characteristics. First, a 3D-FEM model of a real track is constructed, paying special attention to fasteners, and calibrated with displacement data obtained experimentally during a train passage. This numerical model is subsequently used to determine the track vertical and lateral stiffness. This study evidences that although the track can practically lose its lateral stiffness as a consequence of the failure of 7 consecutive fasteners, the vehicle stability would not be necessarily compromised in the flawed zone. Moreover, the results reveal that the uncompensated acceleration and the distance along which the fasteners are failed play an important role in the dynamic behavior of the vehicle-track system, influencing strongly the risk of derailmentMorales-Ivorra, S.; Real Herráiz, JI.; Hernández Gracia, C.; Montalbán-Domingo, L. (2016). Derailment risk and dynamics of railway vehicles in curved tracks: Analysis of the effect of failed fasteners. Journal of Modern Transportation. 24(1):38-47. doi:10.1007/s40534-015-0093-zS3847241Iwnicki S (2006) Handbook of railway vehicle dynamics.CRC Press, Boca RatónJin XS, Wen ZF, Wang KY, Zhou ZR, Liu QY, Li CH (2006) Three-dimensional train-track model for study of rail corrugation. J Sound Vib 293:830–855Jin X, Wen Z, Xiao X (2007) A numerical method for prediction of curved rail wear. Multibody Sys Dyn 18:531–557Li W, Xiao G, Wen Z, Xiao X, Jin X (2011) Plastic deformation of curved rail at rail weld caused by train-track dynamic interaction. Wear 271:311–318Jin X, Wen Z (2008) Effect of discrete track support by sleepers on rail corrugation at a curved track. J Sound Vib 315:279–300Di Gialleonardo E, Bruni S, True H (2014) Analysis of the nonlinear dynamics of a 2-axle freight wagon in curves. Veh Syst Dyn 52(1):125–141Wang K, Liu P (2012) Lateral stability analysis of heavy-haul vehicle on curved track based on wheel/rail coupled dynamics. J Transp Technol 2:150–157Kurzeck B, Hecht M (2010) Dynamic simulation of friction-induced vibrations in a light railway bogie while curving compared with measurement results. Veh Syst Dyn 48:121–138Chen P, Gao L, Hao J (2007) Simulation study on parameters influencing wheel/rail wear in railway curve. China Railway Science 5Sun Y, Cole C, Boyd P (2011) A numerical method using VAMPIRE modelling for prediction of turnout curve wheel-rail wear. Wear 271(1–2):482–491Brabie D (2007) On derailment-worthiness in railway vehicle design. Analysis of vehicle features influencing derailment processes and consequences, PhD Thesis, Royal Institute of Technology, StockholmMatsumoto A, Sato Y, Ohno H, Shimizu M, Kurihara J, Saitou T, Michitsuji Y, Matsui R, Tanimoto M, Mizuno M (2014) Actual states of wheel/rail contact forces and friction on sharp curves—continuous monitoring from in-service trains and numerical simulations. Wear 314:189–197Wang L, Huang A, Liu G (2013) Analysis on curve negotiation ability of the rail vehicle based on SIMPACK. Adv Mater Res 721:551–555Eom BG, Lee H (2010) Assessment of running safety of railway vehicles using multibody dynamics. Int J Precis Eng Manuf 11(2):315–320Zhou L, Shen Z (2013) Dynamic analysis of a high-speed train operating on a curved track with failed fasteners. J Zhejiang Univ Sci A 14(6):447–458Xiao X, Jin X, Wen Z (2007) Effect of disabled fastening systems and ballast on vehicle derailment. J Vib Acoust 129:217–229Shi W, Cai C (2011) Influence of slab track fastener failure on track dynamic performance. In: Advances in environmental vibration-proceedings of the 5th international symposium on environmental vibration, Chengdu, pp 686–692Xiao X, Jin X, Deng Y, Zhou Z (2008) Effect of curved track support failure on vehicle derailment. Veh Syst Dyn 46(11):1029–1059Zakeri J, Fakhari M, Mirfattahi B (2012) Lateral resistance of railway track with frictional sleepers. Proc Inst Civ Eng Transp 165(2):151–155Gibert X, Patel V, Chellappa R (2015) Robust fastener detection for autonomous visual railway track inspection. In: IEEE Winter Conference on Applications of Computer Vision, Waikoloa Beach Hawai, pp 694–701Thompson D, Hemsworth B, Vincent N (1996) Experimental validation of the TWINS prediction program for rolling noise, part 1: description of the model and method. J Sound Vib 193(1):123–135Zakeri JA (2012) Lateral resistance of railway track. In: Perpinya DX (ed) Reliability and safety in railway. InTech Europe, Rijeka, pp 357–374Kernes RG, Edwards JR, Dersh MS, Lange DA, Barkan CP (2011) Investigation of the dynamic frictional properties of a concrete crosstie rail seat and pad and its effect on rail seat deterioration (RSD). Transportation Research Board 91st annual meeting. Railtec, Chicago, IllinoisCarrascal-Vaquero I (2006) Optimization and analysis of the behavior of fastener systems for Spanish high-speed railways. PhD Thesis, University of Cantabria, Santander (In Spanish)Sany J (1996) Another look at the single wheel derailment criteria. In: Proceedings of the IEEE/ASME Joint Railroad Conference, pp 17–22Koo J, Oh H (2014) A new derailment coefficient considering dynamic and geometrical effects of a single wheelset. J Mech Sci Technol 28(9):3483–3498UIC-Leaflet-518 (2009) Testing and approval of railway vehicles from the point of view of their dynamic behaviour-safety-track fatigue-ride quality. Railway Technical Publications, ParisUNE-EN14363:2007 (2007) Railway applications—testing for the acceptance of running characteristics of railway vehicles—testing of running behaviour and stationary tests. AENOR, Madri

A novel mechatronic running gear: concept, simulation and scaled roller rig testing

The basic idea of the concept of the novel mechatronic running gear consists of independently rotating wheels with a mechatronic guidance system to overcome the disadvantages which conventional wheelsets show under certain operating conditions. Especially in narrow curves or at very high speed, oscillation problems linked with noise and increased wear can be observed at conventional wheelsets (curve squeal, hunting instability). Otherwise, vehicles with independently rotating wheels often need a higher maintenance effort to ensure low wear at the wheels. The aim of the concept is the development of a running gear which offers a better running performance than a conventional running gear under all operation conditions in combination with a low maintenance effort. This means a lower emission level of vibrations to the ground and the air as well as less friction at curves and therefore a lower need for traction energy. Additionally, the running gear concept enables more comfortable train concepts such as low floor trams or double deck trains with two continuous decks, because of the abdication of the wheelset axle. The principle is applicable to bogies as well as running gears with a single pair of wheels. These ambitious aims require high demands of the sensor and control system. For instance, the sensor must be able to identify the position of the wheels relative to the track and the control system must be fast enough to avoid flange contact even at highly disturbed tracks at high speed. In the first step a scaled 1:5 roller rig is build (picture) and a model of the scaled roller rig is set up as Multi-Body-System (MBS). In the roller rig force-torque-sensors are used as position sensors. The model can be validated by measurements at the test rig. Then the validated model is used for the design process of the control-algorithms which are tested in the roller rig. Only a model-based control system is able to meet the high demands under the different operation conditions of a train. In a second step the developed control algorithms are transferred into a MBS-model of a 1:1 vehicle to demonstrate the functional capability and the advantages of the simulated operation conditions. Currently this work has the function of a demonstrator and to identify the further research emphasis for an implementation in a real vehicle concept. At the end this novel mechatronic running gear will increase the competitiveness and acceptance of the railway by a cost-effective and low emission running gear. This work is integrated in the DLR-Project Next Generation Train

Running dynamics concept with mechatronic guidance

The two-axle intermediate waggons of DLR's Next Generation Train (NGT) have single-axle running gears with independently rotating wheels (IRW) and mechatronic track-guidance. This enables centring in the track and active radial steering for IRW pairs during curve passing. The wheel wear and noise generation can thus be considerably reduced. Multibody simulations are used to verify and optimise the dynamic behaviour. Moreover, detailed approaches for simulating high-frequency wheel-rail dynamics are being introduced in the project

Considerations on Active Control of Crosswind Stability of Railway Vehicles

The DLR research project Next Generation Train deals with concepts, methods and technologies for a very high-speed train in double deck configuration and light-weight design. Due to these three key features crosswind stability is a particular subject of study. It is shown that conventional approaches here fall short of guaranteeing safety in high-wind occurrences according to the given homologation standards. Therefore this paper discusses the feasibility of different approaches to ensure crosswind stability by means of active control. Four different concepts are overviewed, the most promising one is then chosen und examined in detailed multibody simulations that are based on data from wind tunnel measurements of the Next Generation Train

Next Generation Train - Bericht zu den Simulationsrechnungen 2010 (Fahrzeug Systemdynamik)

In diesem Bericht wird der aktuelle Stand der Fahrdynamikauslegung des Next Generation Trains zusammengetragen. Die Auslegung erfolgt mittels Mehr-Körper-System-(MKS)-Simulationen in der Software SIMPACK. Für prinzipielle Vorüberlegungen werden vereinfachte Modelle verelendet. Die Untersuchung der Fahrzeug-Systemdynamik erfolgt an einem Zugmodell bestehend aus vier Mittel- und zwei Endwagen. Ein Ziel dieses Berichts besteht darin, nach zu weisen, dass es mit dem Zugkonzept möglich ist, die im Projektplan vorgegebenen Verschleiß und Komfortziele zu erreichen. Als Ergebnis kann festgestellt werden dass dies prinzipiell – mit entsprechendem Aufwand – möglich ist. Darüber hinaus werden verschiedene Erkenntnisse gewonnen, die für andere Teilprojekte im NGT relevant sind

High-speed rail vehicles: State of the art and further developments

Worldwide a lot of high speed railways are successfully operating. Until the 1970s, the market share of the European railways in passenger transport decreased strongly due to the fierce competition of individual motor car traffic and of civil aeronautics. The development of high-speed trains and the construction of new high-speed lines, which started in Europe at the end of the 1960s, helped the railway companies a lot to regain lost market shares based on the developments in Japan, France, Italy and Germany. Currently, high-speed trains provide a short and comfortable travelling at maximum operating speeds up to 380 km/h: New lines are planned or built in many countries. Major developing goals for future high speed trains are focused on higher acceptance by offering higher travelling speeds, improved passenger comfort and a high level of safety as well as on better economic efficiency by a reduced energy consumption per seat and lower life cycle costs. The challenge is especially the goal conflict between the increasing of the speed and the reduction of the energy consumption, because the air resistance is proportional to the square of the speed. For instance, the German ICE 3 high-speed train needs a traction power of 7500 kW for travelling with constant speed of 330 km/h on an even and straight track. More than 90% of this power is needed for negotiation of the air resistance. Therefore the optimisation of the aerodynamic design is one of the key issues for an environment friendly train. The internal DLR research project “Next Generation Train“ (NGT) represents a lot of innovative developments. Nine DLR institutes are engaged in different rail specific topics such as aerodynamics, structural design, energy systems, new materials, passenger comfort, running dynamics and vehicle concepts. The most important target of this project is an energy reduction per seat of 50 % compared to the ICE 3. However, the potential of energy reduction by aerodynamic optimisation is not sufficient for this target. Therefore, the concept of the NGT consists of a high speed double-deck trainset in order to obtain a higher increasing of the capacity (i.e. number of seats) than of the air resistance. The passenger comfort of a double-deck train can be significantly increased by continuous floors on both levels. However, the arrangement of two decks for passengers above a conventional running gear would exceed the admissible height given by the European loading gauge. Therefore, the operation of such a train is impossible in Europe. This requires a novel concept for the running gears to avoid this problem. The axle shaft connecting both wheels of a conventional wheelset is an essential element which enables a passive control system for the running dynamics. Since the wheels need a certain minimum diameter of about 1 m, the space for the axle is no longer available in a double-deck train with continuous floors. Therefore, the mechanical component of the axle is replaced by a mechatronic system. In addition, this mechatronic system offers further benefits by improving the running dynamics and the wear behaviour of the running gears. This example demonstrates how an innovative running gear concept can contribute to an integrated and environment friendly train concept