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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Metro traffic optimisation accounting for the disbenefit of halting between stations

Ueda, Naoki January 2005 (has links)
Computerised regulation for disturbed traffic in metro-type railways is proposed. Previous work has used optimisation techniques to minimise disbenefits to passengers, such as waiting time and journey time, in the objective function. The particular disbenefit of trains being halted between stations is introduced in this thesis, in combination with those already mentioned. An effective method in real operations for preventing trains being halted between stations is to hold trains already at stations and to allow running trains to reach the next station when a particular train departure is delayed. The proposed algorithm uses this ‘stop-all-trains-at-once’ philosophy combined with optimisation ideas, in a sequentially structured approach. A further consideration from real operations is the fact that it is not possible to predict precisely when the delayed train will re-start. Estimates of the re-starting time will improve as the delay increases, and the proposed scheme takes this into account. Numerous simulations were undertaken to investigate the performance of the regulation algorithm. It is shown that the proposed regulation algorithm is effective in reducing the disbenefit to passengers from disturbed traffic for various characteristic metros with different passenger flows.
82

System energy optimisation strategies for DC railway traction power networks

Tian, Zhongbei January 2017 (has links)
Energy and environmental sustainability in transportation are becoming ever more important. In Europe, the transportation sector is responsible for about 32% of the final energy consumption. Electrified railway systems play an important role in contributing to the reduction of energy usage and C0\(_2\) emissions compared with other transport modes. Previous studies have investigated train driving strategies for traction energy saving. However, few of them consider the overall system energy optimisation. This thesis analyses the energy consumption of urban systems with regenerating trains, including the energy supplied by substations, used in power transmission networks, consumed by monitoring trains, and regenerated by braking trains. This thesis proposes an approach to searching energy-efficient driving strategies with coasting controls. A Driver Advisory System is designed and implemented in a field test on Beijing Yizhuang Subway Line. The driver guided by the DAS achieves 16% of traction energy savings, compared with normal driving. This thesis also proposes an approach to global system energy consumption optimisation, based on a Monte Carlo Algorithm. The case study indicates that the substation energy is reduced by around 38.6% with the system optimised operations. The efficiency of using regenerative braking energy is improved to from 80.6 to 95.5%.
83

Realising the potential of rich energy datasets

Ellis, Robert Joseph January 2017 (has links)
In the last twenty years the availability of vast amounts of data has enabled industries to gain insight into numerous aspects of their operation whose trends were previously unknown. The result is an unprecedented ability to predict operational needs, to evaluate performance of individuals or assets and prepare such industries for uncertainties. The rail industry currently produces large amounts of data that are, in many cases, not used to their full potential. The first case study demonstrates a novel method to identify and cluster distinct driver styles in use on a DC rail network. Using the optimal driver styles identified, improved ‘driver cultures’ were designed that are shown to provide up to 10% energy savings without the need for expensive in cab driver advisory systems. The second case study details data taken from a full fleet that were used to develop a statistical method to identify the minimum amount of vehicles that required energy metering whilst still providing an accurate mean energy consumption estimate. The identification of this minimum amount was then used to validate the fleet size intended for partial fleet metering options for UK rail networks.
84

Reducing land take and energy use of high-speed railways through the robust design of operations

Hasegawa, Daisuke January 2017 (has links)
I address the problem of the high capital cost of high-speed railways and the need to reduce their energy use through the design of robust operations at the planning stage. Given the cost structure and benefits of different solutions, reducing the size of termini and maintaining robust operations in and near the termini is identified as a promising option for cost reduction. Two methodologies from manufacturing industry, namely, the Lean principle for cost reduction and the Taguchi method for robust design, are confirmed as suitable tools to realise the objective of improving the design of high-speed railways. I developed a novel approach that combines Lean and Taguchi techniques to deal with characteristic features of high-speed railways, such as the severe requirement for robust operations. Finally, the worth of the combined approach has been demonstrated by means of case studies of current British conventional railway practice, current Japanese high-speed railway operations and the planned High Speed Two (HS2) line. The latter work has shown the possibility of a reduction in the proposed number of platforms at Euston Station, the main terminus of HS2 in London, as well as energy saving for traction.
85

Simulation combined model-based testing method for train control systems

Wang, Yuemiao January 2018 (has links)
A Train Control System (TCS) is utilised to guard the operational safety of the trains in railway systems. Therefore, functional testing is applied to verify consistency between the TCS and specification requirements. Traditional functional testing in TCSs is mainly based on manually designed test cases, which is becoming unsuitable for testing increasingly complex TCSs. Therefore, Model-Based Testing (MBT) methods have been introduced into TCS functional testing, to improve the efficiency and coverage of TCS testing, with application difficulties. To overcome the difficulties of applying MBT methods to test TCSs, the author introduces simulation combined MBT which combines an MBT method with simulation. Modelling method and implementation method for the proposed approach were explained in detail. Two case studies were undertaken to explore the effectiveness of the testing platform developed. The testing results obtained prove that the testing platform can be utilised to implement the functional testing of TCSs. To prove that the MBT platform is effective in detecting errors in the SUT, validation and verification was undertaken, which include validation of specification requirements and verification of the MBT platform. The testing performance is proven to be better than existing MBT methods in terms of coverage and efficiency.
86

A numerical investigation of the effect of crosswinds on the slipstream of a model-scale freight train and associated effects

Flynn, Dominic January 2015 (has links)
A numerical investigation is presented in which the effect of crosswinds on the slipstream of a fully-loaded model-scale freight train is studied. The work used delayed detached-eddy simulation in order to produce accurate time-averaged data and also allowed for the instantaneous flow to be analysed. Significant slipstream amplification is shown for both pressure and velocity transients on the leeward side of the train. The most significant slipstream amplification is observed at the 30° yaw angle case where high velocities remain almost constant at the furthest measurement position from train side. Instantaneous slipstream velocities on the leeward side of the train were inputted into a mathematical model which was used to predict the effect of wind gusts on a representative sample of the population. It was found that at 4 m from train side the person instability due to slipstream amplification for the 30° case is nearly double that from the 10° case. The results presented highlight the potential risk associated with slipstream amplification around freight trains, although due to the immaturity of the field, no amendments are made to the codes of practice.
87

Generalised cost benefit analysis for large infrastructure projects : the case of the Channel Tunnel rail link

Naghashian, Mohammad Hossein January 2015 (has links)
Even in the absence of specific evidence it is surely unthinkable to imagine Napolean Bonaparte himself, when considering the potential benefits of invading England, failing to weigh against them the costs of building a tunnel under \(La\) \(Manche\). In the light of the considerable literature of cost benefit analysis (CBA) and by gathering together several analyses that have been performed on the Channel Tunnel in more recent times, this thesis demonstrates that a comprehensive ‘big picture’ CBA framework is missing, and then provides one: a new methodology, represented in Data Flow Diagram (DFD) form, for the generalised cost benefit analysis of large infrastructure projects.
88

Railway traffic rescheduling approaches to minimise delays in disturbed conditions

Fan, Bo January 2012 (has links)
The advent of modern railway signalling and train control technology allows the implementation of advanced real-time railway management. A number of researchers throughout the world have previously considered the problem of minimising the costs of train delays and have used various optimisation algorithms for differing scenarios. However, little work has been carried out to evaluate and compare the different approaches. Firstly, this thesis compares and contrasts a number of optimisation approaches that have been previously used and applies them to a series of common scenarios. It is found that simple disturbances (i.e. one train delayed) can be managed efficiently using straightforward approaches, such as first-come-first-served. For more complex scenarios, advanced methods are found to be more appropriate. For the scenarios considered in this comparison, ant colony optimisation performed well. Secondly, in order to improve the currently available algorithm so that it can more reliably find optimal or close to optimal results within a practical computation time, a new hybrid algorithm, based on ant colony optimisation, has been developed. In order to evaluate the new approach 100 randomly generated delay scenarios are tested, and a comparison is made between the results of the new algorithm and first-come-first-served, brute force and standard ant colony optimisation. It is shown that the hybrid algorithm has improved performance in terms of optimality and computation speed. Finally, a new multi-stage rescheduling approach for finding an optimal solution over multiple junctions is proposed. A case study is considered, and it is shown that the proposed approach performs well.
89

RAMS management of railway systems

Park, Mun Gyu January 2014 (has links)
Railway RAMS is an engineering discipline that integrates reliability, availability, maintainability and safety characteristics into an inherent design property through systems engineering. This research is to establish a systematic approach of RAMS management for the railway systems engineering through the establishment of the engineering concepts, methods, techniques and tools. For this purpose, the research focuses on three subjects and a case study. Firstly, this research provides a RAMS management systems included railway systems engineering and RAMS management processes so that railway organisations can decide a strategic policy, control functions and coordinate activities related to RAMS management. Secondly, this research provides railway risk assessment methods to assess all of the potential hazards that threaten the railway’s operational objectives and control them within the possible acceptable criteria. Thirdly, this research provides the method that develops RAMS performance specifications appropriate to the RAMS requirements and operational contexts in order to develop RAMS design and its acceptance criteria for implementing the detailed design and/or contract. Finally, this research presents a case study for the risk assessment, using the data collected from the railway industry to demonstrate the proposed risk assessment method and to investigate the RAMS performance of the railway systems and their major failure causes.
90

Optimising AC electric railway power flows with power electronic control

Kulworawanichpong, Thanatchai January 2004 (has links)
The latest generation of AC-fed traction drives, employing high-speed switching devices, is able to control the reactive power drawn from the overhead line by each equipment. If the conditions at each locomotive or train could be fed back to a central control point, it is possible for a centrally located controller to calculate optimal values for the reactive power in each drive and to send those commands back to the individual equipment. In this thesis, AC railway power flows are optimised in real time and the results are used to achieve some particular system objective via control of the PWM equipment as mobile reactive power compensators. The system voltage profile and the total power losses can be improved while the overall power factor at the feeder substation is also made nearer to unity. For off-line simulation purposes, high execution speeds and low storage requirements are not generally significant with the latest computer hardware. However, this real-time control employs on-line optimising controllers, which need embedded power solvers running many times faster than real time. Thus, a fast and efficient algorithm for AC railway power flow calculation was developed. The proposed scheme is compared to a conventional reactive power compensation, e.g. SVC, and found to be less expensive to implement. Several test cases for AC electric railway systems are examined. The centralised area control system leads to the best improvement where an existing fleet of diode or thyristor phase-angle controlled locomotives is partially replaced with PWM ones, compared to that obtained without compensation or to classical track-side Var compensation methods. From these results, the potential for PWM locomotives to improve overall system performance is confirmed.

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