scholarly journals Auxiliary Stopping Area Layout Method for High-Speed Maglev Operated Bidirectionally on Single Track

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yi Yu ◽  
Pengzi Chu ◽  
Danyang Dong ◽  
Xi Jiang ◽  
Huahua Zhao ◽  
...  
Keyword(s):  
High Speed ◽  
Construction Cost ◽  
Demand Characteristic ◽  
Single Track ◽  
Layout Problem ◽  
Layout Algorithm ◽  
Operation Efficiency ◽  
Safety Operation ◽  
Train Safety ◽  
Double Track

Auxiliary stopping area (ASA) is the necessary emergency facility for train safety of the normal high-speed maglev. The study addresses the ASA layout problem of the high-speed maglev operated bidirectionally on single track. First, an optimization model of the ASA layout for unidirectional double-track lines considering train safety, operation efficiency, and construction cost is established, and two basic methods of the ASA layout are investigated based on the distance demand characteristic of ASAs. Then, the ASA layout problem of bidirectional single-track lines is analyzed, and an ASA two-way coordination layout algorithm (ASA-TWCLA) is proposed. Finally, a numerical experiment is carried out. The results suggest that under the premise of train safety and operation efficiency, compared with using the basic methods separately on the two directions, adopting the ASA-TWCLA algorithm can obtain a more economical ASA layout scheme for the same scenario.

scholarly journals Alternate Double Single Track Lines

2016 ◽  
Author(s):  
Zacarias Grande Andrade ◽  
Paola Moraga Contreras ◽  
Enrique Castillo Ron
Keyword(s):  
Travel Time ◽  
High Speed ◽  
Time Increase ◽  
Single Track ◽  
Maintenance Costs ◽  
Railway Infrastructure ◽  
Double Track

The paper discusses the advantages and shortcomings of alternate double single track (ADST) lines with respect to double track lines for high speed lines. ADST lines consists of sequences of double and single track segments optimally selected in order to reduce the construction and maintenance costs of railway lines and to optimize the timetables used to satisfy a given demand. The single tracks are selected to coincide with expensive segments (tunnels and viaducts) and the double tracks are chosen to coincide with flat areas and only where they are necessary. At the same time, departure times are adjusted for trains to cross at the cheap double track segments. This alternative can be used for new lines and also for existing conventional lines where some new tracks are to be constructed to reduce travel time (increase speed). The ADST proposal is illustrated with some examples of both types (new lines and where conventional lines exist), including the Palencia-Santander, the Santiago-Valparaíso-Viña del Mar and the Dublin-Belfast lines, where very important reductions (90 %) are obtained, especially where a railway infrastructure already exist.DOI: http://dx.doi.org/10.4995/CIT2016.2016.3426

scholarly journals Estimation of conditions of using combined single-track and double-track railways at high-speed traffic

2018 ◽  
Vol 216 ◽  
pp. 02010 ◽  
Author(s):  
Alexei Dmitrenko ◽  
Sergei Karasev ◽  
Alexandra Kalidova ◽  
Dmitry Sivitsky
Keyword(s):  
Simulation Modeling ◽  
High Speed ◽  
Capital Investments ◽  
Single Track ◽  
Railway Transportation ◽  
Relevant Issue ◽  
Important Condition ◽  
High Speed Railway ◽  
Double Track ◽  
Track Line

An important condition when arranging high-speed railway transportation with insignificant traffic is saving of capital investments in construction of new lines or the reconstruction the existing ones. Development of methods for multi-criteria estimation of the possibility of using fully single-track blocks on a line with high-speed traffic, as well as single-track blocks with double-track inserts, is a relevant issue. The purpose of the study is to develop the criteria and the method for estimation of the feasibility of using single-track elements on a line with high-speed traffic. Methods of simulation modeling, mathematical statistics, regression analysis were used. A method that includes estimation of the technological conditions of using single-track elements on a line with high-speed traffic instead of double-track blocks was developed. The method can be used for multi-criteria optimization of the configuration of a combined single-track and a double-track line using single-track elements in high-cost areas.

Dynamic analysis of railway vehicle derailment mechanism in train-to-train collision accidents

2020 ◽  
pp. 095440972095987
Author(s):  
Lin Hou ◽  
Yong Peng ◽  
Dong Sun
Keyword(s):  
Impact Energy ◽  
High Speed ◽  
Railway Vehicle ◽  
Train Track ◽  
Buckling Mode ◽  
Car Body ◽  
Vertical Displacements ◽  
Energy Absorbing ◽  
Safety Operation ◽  
Train Safety

Train collision-induced derailment may result in serious casualties. This study investigates the railway vehicle derailment behaviour and explores the derailment causes in train-to-train impacts. A train-track coupled dynamic model is developed and validated. The lateral ( Yde) and vertical ( Zde) relative displacements of the wheel/rail pair are used for the derailment evaluation. The results show that the wheelset jumping derailment and the saw-tooth buckling mode may occur during the high-speed collisions. Derailment is mainly caused by car body yawing rotation and wheelset lateral and vertical displacements. Yawing and pitching motions of car body influence wheelset displacement significantly. Vehicles with the higher velocity generate more severe derailment behaviour. Under circumstance of the same train impact energy, the higher vehicle mass and greater car numbers have the stabilizing influence for reducing the derailment risk. Increasing the force on the main energy-absorbing structure which is set in the front-end crushing zone of a vehicle to dissipate the train impact energy and the damping coefficient of the secondary yaw damper can decrease the derailment risk. The train safety operation areas and derailment boundaries indicate that the reliability of the Yde criterion is higher.

scholarly journals Process characterization and analysis of ceramic powder bed fusion

2021 ◽  
Author(s):  
Kevin Florio ◽  
Dario Puccio ◽  
Giorgio Viganò ◽  
Stefan Pfeiffer ◽  
Fabrizio Verga ◽  
...  
Keyword(s):  
High Speed ◽  
Ceramic Powder ◽  
Integrating Sphere ◽  
Alumina Powder ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Ceramic Powders ◽  
Pure Alumina ◽  
Powder Bed ◽  
Melt Pool

AbstractPowder bed fusion (PBF) of ceramics is often limited because of the low absorptance of ceramic powders and lack of process understanding. These challenges have been addressed through a co-development of customized ceramic powders and laser process capabilities. The starting powder is made of a mix of pure alumina powder and alumina granules, to which a metal oxide dopant is added to increase absorptance. The performance of different granules and process parameters depends on a large number of influencing factors. In this study, two methods for characterizing and analyzing the PBF process are presented and used to assess which dopant is the most suitable for the process. The first method allows one to analyze the absorptance of the laser during the melting of a single track using an integrating sphere. The second one relies on in-situ video imaging using a high-speed camera and an external laser illumination. The absorption behavior of the laser power during the melting of both single tracks and full layers is proven to be a non-linear and extremely dynamic process. While for a single track, the manganese oxide doped powder delivers higher and more stable absorptance. When a full layer is analyzed, iron oxide-doped powder is leading to higher absorptance and a larger melt pool. Both dopants allow the generation of a stable melt-pool, which would be impossible with granules made of pure alumina. In addition, the present study sheds light on several phenomena related to powder and melt-pool dynamics, such as the change of melt-pool shape and dimension over time and powder denudation effects.

Measurement of the Melt Pool Length During Single Scan Tracks in a Commercial Laser Powder Bed Fusion Process

2017 ◽  
Author(s):  
J. C. Heigel ◽  
B. M. Lane
Keyword(s):  
Laser Power ◽  
High Speed ◽  
Infrared Camera ◽  
Powder Bed Fusion ◽  
Single Track ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool ◽  
Significant Difference ◽  
Scan Speed

This work presents high speed thermographic measurements of the melt pool length during single track laser scans on nickel alloy 625 substrates. Scans are made using a commercial laser powder bed fusion machine while measurements of the radiation from the surface are made using a high speed (1800 frames per second) infrared camera. The melt pool length measurement is based on the detection of the liquidus-solidus transition that is evident in the temperature profile. Seven different combinations of programmed laser power (49 W to 195 W) and scan speed (200 mm/s to 800 mm/s) are investigated and numerous replications using a variety of scan lengths (4 mm to 12 mm) are performed. Results show that the melt pool length reaches steady state within 2 mm of the start of each scan. Melt pool length increases with laser power, but its relationship with scan speed is less obvious because there is no significant difference between cases performed at the highest laser power of 195 W. Although keyholing appears to affect the anticipated trends in melt pool length, further research is required.

Typical Portal Structure for Single Track High Speed Railway Tunnel in Rugged Mountainous Area with High and Abrupt Slope

2014 ◽  
Vol 716-717 ◽  
pp. 342-346
Author(s):  
Xiao Jun Zhou ◽  
Bo Jiang ◽  
Yue Feng Zhou ◽  
Yu Yu
Keyword(s):  
High Speed ◽  
Southwest China ◽  
Earth Pressure ◽  
Mountainous Area ◽  
Single Track ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Railway Line ◽  
Bridge Abutment

On the basis of different landform and multifarious topography in rugged mountainous area in southwest China, typical tunnel portals for single track tunnels in a new high speed railway line have been presented in the paper. The portal comprises headwall, shed tunnel, bridge abutment and its support. Portal with headwall is suitable for tunnel to resist front earth pressure on high and abrupt slope. Shed tunnel is placed in front of headwall so as to prevent rockfall; its outward part is built into a flared one. Meanwhile, the installation of bridge and its abutment are also included in the portal according to landform in the paper.

Study on Derailment Mechanism and Safety Operation Area of High-Speed Trains Under Earthquake

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Liang Ling ◽  
Xinbiao Xiao ◽  
Xuesong Jin
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Vehicle Speed ◽  
Vertical Force ◽  
Explicit Integration ◽  
Running Safety ◽  
Earthquake Motion ◽  
High Speed Trains ◽  
Wheel Loading ◽  
Safety Operation

In order to investigate the derailment mechanism and safety operation area of high-speed trains under earthquake, a coupled vehicle-track dynamic model considering earthquake effect is developed, in which the vehicle is modeled as a 35 degrees of freedom (DOF) multibody system with nonlinear suspension characteristic and the slab track is modeled as a discrete elastic support model. The rails of the track are assumed to be Timoshenko beams supported by discrete rail fasteners, and the slabs are modeled with solid finite elements. The system motion equations are solved by means of an explicit integration method in time domain. The present work analyzes in detail the effect of earthquake characteristics on the dynamical behaviors of a vehicle-track coupling system and the transient derailment criteria. The considered derailment criteria include the ratio of the wheel/rail lateral force to the vertical force, the wheel loading reduction, the wheel/rail contact point traces on the wheel tread, and the wheel rise with respect to the rail top, respectively. The present work also finds the safety operation area, the derailment area, and the warning area of high-speed trains under earthquake, and their boundaries. These areas consist of three key parameters influencing the dynamical behavior of high-speed train and track under earthquake. The three key influencing parameters are, respectively, the vehicle speed and the lateral and vertical peak ground acceleration (PGA) of an earthquake. The results obtained indicate that the lateral earthquake motion has a greater influence on the vehicle dynamic behavior and its running safety compared to the vertical earthquake motion. The risk of derailment increases quickly with the increasing of lateral earthquake motion amplitude. The lateral earthquake motion is dominant in the vehicle running safety influenced by an earthquake. While the vertical earthquake motion promotes jumping of the wheels easily, not easy is flange climb derailment. And the effect of the vehicle speed is not significant under earthquake.

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