Ugur Yildirim

The Application of Automation Theory to Railway Signalization Systems: The Case of Turkish National Railway Signalization Project

Abstract The application of control and automation theory to practical areas can provide significant means for improvement in developing countries like Turkey, where human (brain) power is relatively inexpensive. A possible application area for the well established automation theory is railway signalization, where formal methods are required to be used in order to comply with the related safety standards. Turkish National Railway Signalization Project (TNRSP) is examined in this paper with this perspective as a case study. Development stages, architecture and design of the software produced in this project are briefly discussed.

Interlocking system design for ERTMS/ETCS: An approach with batches Petri nets.

Abstract In order to optimize and to standardize the train traffic across Europe, railway people developed new standards known as European Rail Traffic Management System (ERTMS) that has three levels from conventional rails (level 1) to high speed rails (level 3). The use of this standard is not limited only in Europe and became a widely used standard in Asia and America. In this study, movement of two consecutive trains as moving-blocks on a single railway line is modeled using a hybrid modeling technique known as Batches Petri Nets.

A new voting strategy in Diverse programming for railway interlocking systems

The main issue in controlling systems such as nuclear power reactors or railway systems is to provide safety at the highest level where risk ratio is high and sometimes small errors might result with death of several people. In order to improve reliability and keep safety of such systems at the required level by decreasing common cause failures at the same time Diverse programming (which is synonymous with N-version programming) technique can be used. In this study an example railway interlocking architecture is explained and a new voting strategy is also proposed.

Feasibility of brain stroke imaging with microwaves

This paper investigates feasibility of detection of blooded area in a realistic head phantom with microwave imaging. Realistic phantom is illuminated by 36 line sources and the scattering field data is calculated numerically with method of moments. Additive white Gaussian noise with 20 dB is added for more realistic scenario. Contrast Source Inversion method is used to reconstruct the blooded area. Simulations are done at different operating frequencies of 500 MHz, 800 MHz and 1000 MHz. Moreover, results either with electrically different background mediums or free space are discussed in this study. The numerical results show that it is possible to determine the square shape blooded area with size about 2.6cm × 2.6cm between the 800–1000Mhz frequency range in the dielectric matching medium.

Automatic Interlocking Table Generation for Railway Stations Using Symbolic Algebra

Abstract Interlocking is the most important component of a signalization system, which ensures safe travel and transportation. An interlocking system helps movement of trains on desired routes in fixed block signaling systems. The first step in the design of interlocking systems is to generate interlocking tables. Generation of interlocking tables for small scaled stations or railway yards can be realized easily. However, when the topology of the station is complicated, generation of the corresponding interlocking table becomes considerably difficult. In this study, a program that automatically generates interlocking tables for a given railway yard is explained. One of the main advantages of the program is that, switches and signal lights are placed automatically for a given station or railway yard depending on the topology.

Automatic Interlocking Table Generation for Non-ideal Railway Yards

Abstract Interlocking systems that can be regarded as the main decision making component of fixed block railway signaling systems, are directly responsible for ensuring the safe movements of trains. Software of an interlocking system depends on the interlocking table of the related railway yard. Although there are tools for automatic interlocking table generation, these tools generally do not consider non-ideal situations like non-signaled track or non-standard use of switches or signals. In this study, an efficient automatic interlocking table generation tool was proposed considering these non-ideal situations.

N-version Programming for Railway Interlocking Systems: Synchronization and Voting Strategy

Abstract The main issue in controlling safety-critical systems such as nuclear power reactors or railway signalization systems where risk ratio is at the highest level because small errors might result in hazardous accidents (e.g. death or injury of several people) is to satisfy safety-related standards and provide high-safety with high-reliability. In order to improve reliability and safety of such systems to the required level by decreasing common-cause failures at the same time, diverse programming (or N-version programming) technique where N-different independently designed modules run in parallel on the same input output specifications can be used. In this study, a new bitwise voting strategy based on safe-states of variables is proposed and possible critical races between modules those run in a parallel manner are determined. Solutions for critical races are also explained.

A symbolic PI tuning method for first order systems with time delay

This paper presents a symbolic PI tuning method for first orders systems with time delay based on Pade approximation. The presented method is very easy to use like well-known methods such as Ziegler-Nichols and Cohen-Coon. Besides its easiness, the method performs a faster step response and no overshoot. Furthermore, it provides a good robust performance.

Modeling and control of under-damped second order systems with dead-time and inverse response

Systems with inverse response are difficult to be identified because of the existence of at least one zero at the right half s-plane. However, it is important to obtain the transfer function as accurately as possible for such systems to be able to provide the desired performance using a controller. If the system has dead-time, the design problem becomes more complicated. This paper presents a new modeling method for under-damped second order systems with an inverse response to overcome the difficulties both in the analysis and design. Besides, a PID controller design in discrete-time domain is also introduced to provide a good performance in the closed-loop. The performance of the proposed modeling and control technique is demonstrated on an example using simulations.

Comparison of the Parallel and Serial Architectures for N-Version Programming as Applied to Railway Interlocking Systems

Abstract The concept of functional safety gains importance with the increasing number of hazardous accidents in the railway industry. In literature, some hardware and software architectures are proposed for the functional safety. As N-version programming is getting popular as preferred software architecture in railway industry, the effect of various hardware implementations of N-version programming on the functional safety remains unclear. In this study, two different hardware setups will be evaluated for N-version programming. After the effect of these hardware setups on the functional safety is analyzed, the effects on the hardware usage and overall response time will be tested on a sample train station.