High Speed Railway Wireless Communications: Efficiency v.s. Fairness

High speed railways (HSRs) have been deployed widely all over the world in recent years. Different from traditional cellular communication, its high mobility makes it essential to implement power allocation along the time. In the HSR case, the transmission rate depends greatly on the distance between the base station (BS) and the train. As a result, the train receives a time varying data rate service when passing by a BS. It is clear that the most efficient power allocation will spend all the power when the train is nearest from the BS, which will cause great unfairness along the time. On the other hand, the channel inversion allocation achieves the best fairness in terms of constant rate transmission. However, its power efficiency is much lower. Therefore, the power efficiency and the fairness along time are two incompatible objects. For the HSR cellular system considered in this paper, a trade-off between the two is achieved by proposing a temporal proportional fair power allocation scheme. Besides, near optimal closed form solution and one algorithm finding the $\epsilon$-optimal allocation are presented.Comment: 16 pages, 6 figure

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. 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Desain Produk Instalasi Unit Kesehatan dengan Refunction Container Berkonsep Semi Permanen (Studi Kasus: Lapangan Thor Surabaya)

Kota Surabaya memiliki pelabuhan peti kemas tersibuk kedua di Indonesia dan terbesar di Indonesia Bagian Timur yakni Pelabuhan Tanjung Perak. Data yang diambil melalui situs resminya bahwa arus petikemas melalui Terminal Petikemas Surabaya (TPS) hingga bulan Desember tahun 2021 tercatat sebanyak 1.415.644 TEUs. Jumlah ini meningkat 2,6% dari periode yang sama pada tahun 2020 lalu. Dari data diatas, sebuah petikemas dapat berpotensi untuk di ubah dan dijadikan sebuah produk yang berguna untuk khalayak umum daripada berakhir di tempat besi tua. Tujuan yang ingin dicapai peneliti pada Tugas Akhir ini adalah menghasilkan Desain Produk Unit Kesehatan dengan Refunction Container Berkonsep Semi Permanen guna melayani dan membantu masyarakat di sekitar lokasi studi kasus untuk perawatan kesehatan seperti cedera atau kecelakaan yang disebabkan oleh aktifitas olahraga. Peneliti mengambil topik tersebut karena dilatar belakangi oleh beberapa hal yaitu, 1) Ketersediaan shipping container bekas yang ada di terminal peti kemas cukup melimpah di pelabuhan namun terbengkalai dan hanya menjadi besi tua. 2) Unit kesehatan pada Lapangan Thor Surabaya dirasa kurang laik pakai. 3) Konsep semi pemanen memungkinan shipping container dengan mudah dalam proses bongkar pasang 4) Desain unit pelayanan kesehatan masih kurang menarik perhatian masyarakat sekitar. 5) Fasilitas penunjang seperti tempat duduk maupun toilet dapat menambah nilai fungsional dari sebuah unit kesehatan berbasis shipping container

Reduced models for dynamic analysis of high-speed railway bridges

Today a dynamic analysis is often performed with the use of advanced finite element software. An advanced model normally produces precise results. Analyzing these large models of bridges is however time consuming and a detailed description of the geometry, supports and material properties must be known. In an early stage of a project a reduced model could significantly reduce the time needed to perform the final dynamic analysis. The aim of this thesis was to investigate the dynamic response of railway bridges for high-speed trains and to develop a reduced model that can be used early in a project, to provide a quick dynamic analysis of bridges with several spans. The reduced model was based on the fact that the fundamental dynamic behavior of certain type of bridges may be described by the dynamic behavior of 2-dimensional Bernoulli beam elements. The bridge model was developed as a MATLAB function and consists of a selectable number of Bernoulli beam elements. Three different approaches of modeling the train load were compared. The first method of modelling the train was made as moving point-loads, the second as a distributed load and the third as a separate mass and spring model. In order to make the developed MATLAB function easy to use, to perform quick analysis and with good accuracy, the numbers of input parameters were minimized. This was made by setting some of the properties of the reduced model as fixed standard values. The values were based on result of extensive modelling studies. Finally, two bridges with realistic dimensions and materials were analyzed using both the reduced model and a more advanced model. The reduced model was proved to provide basically the same results as the more advanced model. The time needed to model the bridge and to perform the analysis was approximately 10 minutes when using a standard home pc, which was a significant reduction of the time needed to make the advanced model and to perform the analysis

Research and analysis of elastic strip fatigue under stress controlled loading mode

Fastener technology is a key technology of Ballastless track structure in high-speed railway, and the elastic strip is the key component to realize fastener function. To this end, a special loading fixture is fabricated to explore the performance of the elastic strip under fatigue load. The working state of the elastic strip was simulated through the fatigue testing machine, and the stress-controlled loading modes and four loading amplitudes (25±5kN, 25±7.5kN, 25±10kN, 25±12.5kN) are investigated. The pressure control method is used for fatigue tests, and the results show that: (1) As the load amplitude increases, the fatigue life decreases sharply and its decreasing speed is greater than the increasing speed of load amplitude; (2) The buckling pressure and displacement curves of the elastic strip have the characteristics of "increasing step-by-step" and "decreasing step-by-step"; (3) In the fatigue test, the attenuation of buckling pressure is 22% - 33% and the displacement at the front end of the ring is 18% - 25%; (4) According to the results, the buckling pressure curve and the displacement curve of the ring in the elastic strip are drawn, and the equations of them are fitted to estimate the service performance of the elastic strip

Dynamic Analysis of a High Speed Train

Studies in modern high-speed traction need to develop detailed equations to formulate a complete electromechanical model that represents the dynamic coupling of electrical and mechanical phenomena. Starting from Lagrange and Park theories, and after recalling the general criteria for the setup of the two distinct mechanical and electrical subsystems, the new formalization of a complete dynamic model with specific reference to a train dedicated to high-speed services is hereby presented. Simulations are carried out with relation to two conditions of particular interest in the application side, i.e., the steady-state condition and the three-phase short-circuit fault at a speed of 100 km/h. Representative of the dynamics of each single component, the investigation in particular focuses on the transmission organs (rotor, Cardan joint, and gear case) and the relevant torques associated with the short-circuit dynamics