Railway technology publications on train simulation, system modelling & safety assessment
Bookmark and Share

Cecube technology consulting

SITE MAP INDEXING PAGE

Add Cecube Online to Favourites and Bookmarks

NEWSLETTERS

1. 'Railway System Models with re-usable Software Component Code'

Off the shelf components have often been tested in real life use and besides reducing development effort they also reduce testing. Bugs, compatibility problems, development needs are easier to find when code has been widely used. It is estimated that more than half of all programming effort could be saved with careful study and use of existing components, providing an opportunity to improve productivity. This requires changes in attitudes at an organizational and technological level. Re-usable code should not be thought of as a 'low cost semi-professional' purchase, but a better product at a cost-effective price.
Read more about the case for code components ...

Code Components Debate (pdf 26k)


2. 'Topological Simulation of Railway Interfaces'

Railway stations, junctions, tunnels and trunk routes frequently involve more than one network, and consequently potential network interaction. No text book solution exists to realistically calculate coupling effects at these network interfaces of varied complexity and individuality. At least two interacting coupling mechanisms are present (conductive and inductive), where conductor impedance paths are highly frequency dependent and non-linear. Over simplification of earth arrangements and failure to account for ground dispersion effects produces poor manually calculated results. TOP-FACE automates the mathematical complexity in a generalised solution, providing short execution time and rapid reconfiguration for addition or removal of features without interface redesign.
Learn where and how this modelling tool is applied ...

TOP-FACE simulation (pdf 163k)

ARTICLES

1. 'Algebraic Optimisation of Regenerative Railway Systems for Minimum Run Time'

Concern about environmental issues is raising interest in using the regenerative capabilities of modern rolling stock. The first part in a series of articles shows analytically how a traction equipment designed to save energy may also save time ...

Regeneration - Part 1

2. 'Optimisation of Regenerative Rapid Transit Systems to Determine Run Time versus Energy Loss Relationship'

The second article derives the energy consumption function that subsequently quantifies the benefit ...

Regeneration - Part 2

Cecube News Feed RSS News Feed for the rest of the articles in this keynote series on Regenerative Brake.

HELPFUL HINTS

A number of helpful control system support documents are found below

  • BODE PLOT
    Electrical, mechanical and control engineers frequently encounter second order systems because they occur naturally in many practical situations. Tuned LC filters and the spring-mass-damper are two such commonly occurring examples. Understanding the relationship and sensitivity of amplitude overshoot to phase shift () is critical to prescribing sufficient damping. One of the best ways to achieve this has remained unchanged over the past 50 years, and that is to visually establish where the system sits on a BODE PLOT GAIN AND PHASE DIAGRAM. The consequence of damping variation (e.g. = 0.5*R*sqrt[C/L] for a tuned filter) due to manufacturing tolerance or temperature effects is then easily identified.
  • NICHOLS CHART
    While Bode gives a clear measure of predicted stability, it requires experience and skill to interpret from the Bode plot the performance of the system in closed loop. Nichols Charts perform this function. By plotting the open loop gain (Y axis) and phase (X axis) of the system transfer function on the rectangular co-ordinates, the closed loop response is shown by the intersection of curved contours with the line plotted. For each point (or frequency) on the line it is possible to read off the resulting closed loop GAIN and PHASE from the NICHOLS CHART. It achieves this by mapping the transform G(s) => G(s)/[1 + G(s)]. Stability is assured provided the (-1, 0) point is not enclosed by the line representing the open loop transfer function.
  • Z-PLANE MAP
    Bode and Nichols provide a graphical approach to control loop design and stability, but these techniques were developed for linear analogue systems. Most modern controls are processor based digital systems. To analyse discrete data systems the closed loop characteristic equation [1 + G(z)] must be solved, where z-1 represents the delay sampling period. For the often occurring second order digital system, the position of the equation roots determine the DAMPING FACTOR from Z-PLANE CONTOUR MAP. Stability is assured provided the roots of the characteristic equation lie within the unit circle.
  • If you are a professional engineer and a member of the IET (and some other institutions) you can set up an institution based email re-routing service. Why might you want to do this? If you do not have a personal domain name but wish to conduct personal email web communications with a professional / business appearance, when external to your organisation or work place. Many consider the format of the alias address, jbloggs@theiet.org, preferable to a common free domain tag. However, used in conjunction with a Gmail account you also benefit from superior anti-spam email facilities. The service is free and just requires IET website registration, an advisable step for any member. The best way to locate the application page after successful login is to search locally for "IET email alias".
Contact Details top of page

Railway Publications

Custom Search

Loading news - Please wait

IEEE Letters

End of links