A preventive, opportunistic maintenance strategy for the catenary system of high-speed railways based on reliability

2019 ◽  
Vol 234 (10) ◽  
pp. 1149-1155
Author(s):  
Hongbo Cheng ◽  
Yufan Cao ◽  
Jiaxin Wang ◽  
Wei Zhang ◽  
Han Zeng
Keyword(s):  
High Speed ◽  
Maintenance Cost ◽  
Opportunistic Maintenance ◽  
Maintenance Schedule ◽  
Maintenance Time ◽  
Study Results ◽  
Railway System ◽  
Vital Component ◽  
Catenary System ◽  
Maintenance Schedules

The catenary is a vital component of the electrified railway system. It consists of many parts which are interrelated; the maintenance schedule of the catenary system should consider the influence of the interrelationship. In this study, a preventive, opportunistic maintenance method is proposed to schedule the maintenance process of the catenary system. First, the reliability of the key parts of the catenary is modeled using Weibull distribution. Second, a reliability margin is proposed to expand the maintenance time from point to interval, and the reliability margin is optimized to minimize the maintenance cost. Then, a preventive opportunistic maintenance schedule can be arranged on the basis of the optimal reliability margin. Case study results verify that the proposed preventive opportunistic maintenance method can reduce the number of maintenance schedules and can effectively save the maintenance cost.

scholarly journals Maintenance Grouping Optimization for Offshore Wind Turbine Considering Opportunities Based on Rolling Horizon Approach

2018 ◽  
Vol 25 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Yang Lua ◽  
Liping Suna ◽  
Jichuan Kanga ◽  
Xinyue Zhang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Poor Performance ◽  
Offshore Wind ◽  
Maintenance Cost ◽  
Offshore Wind Turbine ◽  
Rolling Horizon ◽  
Imperfect Maintenance ◽  
Opportunistic Maintenance ◽  
Maintenance Schedule

Abstract In future, offshore wind turbines may be consider a crucial part in the supply of energy. Maintenance processes are directed to attain a safe and reliable operation of offshore machines and wind turbines. In this paper, an opportunistic maintenance strategy for offshore wind turbine is proposed, considering imperfect maintenance and the preventive maintenance durations. Reliability Centric Maintenance serves as a proactive tactic to operations and maintenance by inhibiting the possible reasons of poor performance and controlling failures. Other components can implement the opportunistic preventive maintenances if one component has reached its reliability threshold. According to the rolling horizon approach, it is of great importance to update the maintenance planning for the sake of the short-term information. By figuring out the best combination, the maintenance schedule in the mission time has been finally determined. Failure information are obtained from previous studies to accomplish the calculations. The outcomes indicate that the maintenance cost has been dramatically reduced through the application of opportunistic maintenance.

Modeling the development of rail corrugation to schedule a more economical rail grinding

2019 ◽  
Vol 234 (4) ◽  
pp. 370-380 ◽  
Author(s):  
Hirofumi Tanaka ◽  
Masashi Miwa
Keyword(s):  
Surface Roughness ◽  
Growth Curves ◽  
Minimum Cost ◽  
Maintenance Cost ◽  
Rail Corrugation ◽  
Maintenance Schedule ◽  
Rail Grinding ◽  
Noise Vibration ◽  
Maintenance Schedules ◽  
The Cost

Rail corrugation should be managed appropriately, as it causes noise, vibration, and degradation of track components and materials. Generally, rail corrugation is managed with the removal of rail surface roughness by rail grinding. However, in many cases, rail corrugation will reoccur after the rail is ground, thereby making the management of the phenomenon difficult for railway operators. For the proper management of rail corrugation, it is necessary to understand the development of rail corrugation and model it mathematically. However, this effort has not been made in previous studies. This paper investigates an efficient method for scheduling a regular grinding maintenance to manage rail corrugation. Using regularly measured data about rail surface roughness on a commercial line, a mathematical model was developed to estimate the growth of rail corrugation. This model was utilized to estimate the effects of the remaining roughness after rail grinding on the maintenance cost and to optimize the maintenance schedule. First, it was confirmed that the development of rail surface roughness of rail corrugation can be expressed in three phases and can be modeled by fitting the functions of growth curves to measurements of rail surface roughness recorded over a long period. Next, the rail grinding strategy was examined by applying this model to realize both effective and economical strategies for the maintenance of rail corrugation. This study confirmed that maintenance costs can be reduced by rail grinding that removes almost all of rail corrugation. In the case of ballasted tracks, it has been found that the optimal grinding schedule can reduce the cost of rail grinding as well as the cost of tamping. These findings can be applied by railway operators tasked with managing maintenance schedules for railway lines at a minimum cost.

scholarly journals Development of requirements for logic controls of the speed lines catenary system maintenance

2021 ◽  
Vol 2021 (4) ◽  
pp. 8-17
Author(s):  
Mokhirbek F. MUKHAMEDZHANOV ◽  
Keyword(s):  
High Speed ◽  
Practical Importance ◽  
Current Collector ◽  
Actual State ◽  
State Monitoring ◽  
Current Collection ◽  
Maintenance Schedule ◽  
Logic Control ◽  
Catenary System ◽  
System Life

Objective: To develop requirements for the organization of maintenance of the catenary system based on the actual state indicated by the digital diagnostic and monitoring platform in the logic control system for high-speed traffic. Methods: An overview analysis of high-speed catenary system diagnostics and monitoring systems is applied. Results: The systems of monitoring and automated control of catenary system devices in high-speed lines have been studied. The analytical findings as regards the maintenance methods according to the preventive maintenance schedule and based on the actual state monitoring data have been presented. Requirements for diagnostic and monitoring devices 15 of the high-speed lines catenary system have been formulated, aimed at improving the quality attributes of current collection. Practical importance: A structural diagram of quality diagnostics and monitoring for the current collection in the high-speed Current Collector–Catenary system was obtained. The design concept of a prin-cipal model of logic control of the catenary system life cycle has been developed

scholarly journals Risk-Based Predictive Maintenance for Safety-Critical Systems by Using Probabilistic Inference

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Tianhua Xu ◽  
Tao Tang ◽  
Haifeng Wang ◽  
Tangming Yuan
Keyword(s):  
High Speed ◽  
Probabilistic Inference ◽  
Evolution Model ◽  
Predictive Maintenance ◽  
Maintenance Cost ◽  
Dynamic Evolution ◽  
Critical Systems ◽  
Maintenance Time ◽  
Safety Constraints ◽  
Optimal Maintenance

Risk-based maintenance (RBM) aims to improve maintenance planning and decision making by reducing the probability and consequences of failure of equipment. A new predictive maintenance strategy that integrates dynamic evolution model and risk assessment is proposed which can be used to calculate the optimal maintenance time with minimal cost and safety constraints. The dynamic evolution model provides qualified risks by using probabilistic inference with bucket elimination and gives the prospective degradation trend of a complex system. Based on the degradation trend, an optimal maintenance time can be determined by minimizing the expected maintenance cost per time unit. The effectiveness of the proposed method is validated and demonstrated by a collision accident of high-speed trains with obstacles in the presence of safety and cost constrains.

Running safety evaluation of a 350 km/h high-speed freight train negotiating a curve based on the arbitrary Lagrangian-Eulerian method

2021 ◽  
pp. 095440972098628
Author(s):  
Gongxun Deng ◽  
Yong Peng ◽  
Chunguang Yan ◽  
Boge Wen
Keyword(s):  
High Speed ◽  
Safety Evaluation ◽  
Interaction Model ◽  
Arbitrary Lagrangian Eulerian ◽  
Railway Transportation ◽  
Freight Train ◽  
Fluid Structure ◽  
Running Safety ◽  
Study Results ◽  
Fill Level

To adapt to the rapid growth of the logistics market and further improve the competitiveness of railway transportation, the high-speed freight train with a design speed of 350 km/h is being developed in China. The safety of the train under great axle load of 17 t and dynamic load is unknown. This paper is aimed to study the running safety of the high-speed freight train coupled with various cargo loading conditions negotiating a sharp curve at high velocity. A numerical model integrated a fluid-structure coupled container model and the nonlinear high-speed freight train was set up by the software of LS-DYNA. The fluid-structure interaction model between the container and fluid cargo was established using the Arbitrary Lagrangian-Eulerian (ALE) method. Two influencing parameters, including the cargo state in the container and the fill level, were selected. The study results showed that the wheelset unloading ratio and overturning coefficient could be significantly affected by the liquid sloshing, while the influence of sloshing on the risk of derailment was slight. In general, increasing the cargo filling rate would contribute to vehicle operation safety. In conclusion, this study would provide theoretical help for the running safety of the newly designed high-speed freight train.

Gas bubble induced scalings in geothermal systems

2021 ◽  
Author(s):  
Lilly Zacherl ◽  
Thomas Baumann
Keyword(s):  
Ph Value ◽  
Saturation Index ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Geothermal Systems ◽  
Injection Wells ◽  
Term Operation ◽  
Maintenance Schedule ◽  
Local Experience ◽  
Maintenance Schedules

<p>Scalings in geothermal systems are affecting the efficiency and safety of geothermal systems. An operate-until-fail maintenance scheme might seem appropriate for subsurface installations where the replacement of pumps and production pipes is costly and regular maintenance comprises a complete overhaul of the installations. The situation is different for surface level installations and injection wells. Here, monitoring of the thickness of precipitates is the key to optimized maintenance schedules and long-term operation.</p><p>A questionnaire revealed that operators of geothermal facilities start with a standardized maintenance schedule which is adjusted based on local experience. Sensor networks, numerical modelling and predictive maintenance are not yet applied. In this project we are aiming to close this gap with the development of a non-invasive sensor system coupled to innovative data acquisition and evaluation and an expert system to quantitatively predict the development of precipitations in geothermal systems and open cooling towers.</p><p>Previous investigations of scalings in the lower part of production pipes of a geothermal facility suggest that the disruption of the carbonate equilibrium is triggered by the formation of gas bubbles in the pump and subsequent stripping of CO<sub>2</sub>. Although small in it's overall effect on pH-value and saturation index, significant amounts of precipitates are forming at high volumetric flow rates. To assess the kinetics of gas bubble induced precipitations laboratory experiments were run. The experiment addresses precipitations at surfaces and at the gas bubbles themselves.</p>

Synthesis and Analysis of a Combined Magnetic and Gas Dynamic Suspension for a Model Range of New-Generation High-Speed Micro Gas Turbine Power Units

2021 ◽  
pp. 5-17
Author(s):  
Sergey A. GANDZHA ◽  
◽  
Nikolay I. NEUSTROEV ◽  
Pavel A. TARANENKO ◽  
◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Turbine Unit ◽  
Electrical Machine ◽  
Gas Turbine Unit ◽  
Micro Gas Turbine ◽  
Gas Dynamic ◽  
Study Results ◽  
Generator Design ◽  
New Generation

The modern power industry is characterized by intense development of distributed generation, with which numerous sources of different capacities are connected into a single network. This makes it possible to improve the reliability of the entire system, since the probability of several sources to fail simultaneously is quite low. Electric generation based on high-speed gas turbine units accounts for a significant share in the overall balance, due to which scientific research and new engineering solutions in this area are important and relevant. An innovative design of a high-speed gas turbine unit based on a switched axial generator is proposed. This electrical machine has a diamagnetic armature, which eliminates magnetic losses, due to which better efficiency of the power unit is achieved and its design is simplified. The high speed of rotation and the presence of critical resonant rotor speeds generated the need to adopt appropriate engineering decisions in regard of its supports. A combined suspension involving the use of magnetic and gas-dynamic bearings is proposed. The magnetic bearings support the gas turbine unit operation at low speeds during its acceleration, and the gas-dynamic bearings support its operation at high nominal speed. The generator design and the combined suspension layout are shown. The numerical analyses of magnetic and gas-dynamic bearings for a gas turbine unit for a capacity of 100 kW and rotation speed of 70 000 rpm are given. The study results can be used for a series of gas turbine units with capacities ranging from 10 to 500 kW. In our opinion, this concept is competitive with modern analogs with a radial generator design.

Failure analysis and optimization of integral droppers used in high speed railway catenary system

2018 ◽  
Vol 91 ◽  
pp. 496-506 ◽  
Author(s):  
Xi-Yang Liu ◽  
Jin-Fang Peng ◽  
De-Qiang Tan ◽  
Zhi-Biao Xu ◽  
Jian-Hua Liu ◽  
...  
Keyword(s):  
Failure Analysis ◽  
High Speed ◽  
High Speed Railway ◽  
Catenary System

scholarly journals Improving the mechanical properties of tool steel by induction chemical-thermal treatment

2021 ◽  
Vol 2086 (1) ◽  
pp. 012200
Author(s):  
P Palkanov ◽  
V Koshuro ◽  
A Fomin
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Thermal Treatment ◽  
Tool Steel ◽  
High Speed ◽  
Nitride Layer ◽  
Surface Microhardness ◽  
Gaseous Nitrogen ◽  
Gradient Diffusion ◽  
Study Results

Abstract The study results of the structure and microhardness of the surface layer of high-speed tool steel after induction chemical-thermal treatment in a gaseous nitrogen-containing medium at a temperature of 900–1100 °C were presented. Due to the strengthening treatment of products a gradient diffusion nitride layer with a thickness of about 200 μm and a surface microhardness of 1950±70 HV1 98 was formed.

scholarly journals Numerical simulation and experimental research of cavitation nozzle based on equation curve

2021 ◽  
Author(s):  
Lifu Wang ◽  
Dongyan Shi ◽  
Zhixun Yang ◽  
Guangliang Li ◽  
Chunlong Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
High Speed ◽  
Quadratic Equation ◽  
Outer Contour ◽  
Study Results ◽  
Fluent Software ◽  
The Impact ◽  
Better Than

Abstract To further investigate and improve the cleaning ability of the cavitation nozzle, this paper proposes a new model that is based on the Helmholtz nozzle and with the quadratic equation curve as the outer contour of the cavitation chamber. First, the numerical simulation of the flow field in the nozzle chamber was conducted using FLUENT software to analyze and compare the impact of the curve parameters and Reynolds number on the cleaning effect. Next, the flow field was captured by a high-speed camera in order to study the cavitation cycle and evolution process. Then, experiments were performed to compare the cleaning effect of the new nozzle with that of the Helmholtz nozzle. The study results demonstrate that effective cavitation does not occur when the diameter of the cavitation chamber is too large. For the new nozzle, with the increase of the Reynolds number, the degree of cavitation in the chamber first increases and then decreases; the cleaning effect is much better than that of a traditional Helmholtz nozzle under the same conditions; the nozzle has the best cleaning effect for the stand-off distance of 300 mm.

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