基于梯形逻辑的联锁系统形式化验证方法

铁路联锁系统设计通常采用梯形逻辑进行建模。为了实现对铁路联锁系统进行形式化验证的目的,根据梯形逻辑的状态变迁语义,将梯形逻辑表示的联锁系统模型转换成模型检测工具NuSMV的语言,并将铁路联锁系统的安全需求表示为计算树逻辑(CTL),最后实现基于NuSMV的铁路联锁系统设计模型的形式化验证。     

Automated Verification of Signalling Principles in Railway Interlocking Systems

In this paper we present a verification strategy for signalling principles for the control of a railway interlocking system written in ladder logic. All translation steps have been implemented and tested on a real-world example of a railway interlocking system. The steps in this translation are as follows: 1. The development of a mathematical model of a railway interlocking system and the translation from ladder logic into this model. 2. The development of verification conditions guaranteeing the correctness of safety conditions. 3. The verification of safety conditions using a satisfiability solver. 4. The generation of safety conditions from signalling principles using a topological model of a railway yard.     

Automatic instantiation of abstract tests on specific configurations for large critical control systems

Computer‐based control systems have grown in size, complexity, distribution and criticality. In this paper a methodology is presented to perform an ‘abstract testing’ of such large control systems in an efficient way: an abstract test is specified directly from system functional requirements and has to be instantiated in more test runs to cover a specific configuration, comprising any number of control entities (sensors, actuators and logic processes). Such a process is usually performed by hand for each installation of the control system, requiring a considerable time effort and being an error‐prone verification activity. To automate a safe passage from abstract tests, related to the so‐called generic software application, to any specific installation, an algorithm is provided, starting from a reference architecture and a state‐based behavioural model of the control software. The presented approach has been applied to a railway interlocking system, demonstrating its feasibility and effectiveness in several years of testing experience. Copyright © 2008 John Wiley & Sons, Ltd.     

Towards model checking executable UML specifications in mCRL2

We describe a translation of a subset of executable UML (xUML) into the process algebraic specification language mCRL2. This subset includes class diagrams with class generalisations, and state machines with signal and change events. The choice of these xUML constructs is dictated by their use in the modelling of railway interlocking systems. The long-term goal is to verify safety properties of interlockings modelled in xUML using the mCRL2 and LTSmin toolsets. Initial verification of an interlocking toy example demonstrates that the safety properties of model instances depend crucially on the run-to-completion assumptions.     

Using symbolic CTL model checking to verify the railway stations of Hoorn-Kersenboogerd and Heerhugowaard

We examine the application of symbolic CTL model checking to railway interlocking software. We show that the railway interlocking systems examined exhibit the characteristics of robustness and locality, and that these characteristics allow optimizations to the model checking algorithms not possible in the general case. In order to gain a better understanding of robustness and locality, we examine in detail a small railway interlocking. Published online: 9 October 2001     

Automated generation of formal safety conditions from railway interlocking tables

This paper describes a tool for extracting formal safety conditions from interlocking tables for railway interlocking systems. The tool has been applied to generate safety conditions for the interlocking system at Stenstrup station in Denmark, and the SAL model checker tool has been used to check that these conditions were satisfied by a model of the relay circuits implementing the interlocking system at Stenstrup station.     

霍尔车轮传感器的研制

铁路车轮传感器是铁路监测及控制的重要基础设备。近年,徐州电务段完成了铁路霍尔车轮传感器的研制和试验。该研制和试验基于霍尔效应原理,研制出的产品比采用LC谐振原理的车轮传感器灵敏度高、抗干扰能力强、抗振动性能强、体积小;与国外同类产品相比,功耗在无车占用的情况下低75%,在有车占用情况下低50%,输出电压的稳定度提高了10%,电源电压范围扩展了3倍,在钢轨出现"肥边"的情况下,灵敏度显著提高,满足了铁路编组场计算机系统对车列的定位和速度检测的要求。     

嵌入式联锁控制器软件体系结构动态建模研究

首先应用π演算和Petri网的相关理论,建立了嵌入式联锁控制器软件体系结构抽象模型ISAM;然后对ISAM模型的动态演化、一致性和死锁进行了深入研究;最后应用ISAM抽象模型,对嵌入式联锁控制器软件系统进行分析。     

轨道交通联锁领域特定语言的形式化

作为轨道交通系统的核心子系统之一，对联锁系统进行形式化建模与分析，是保证其安全性的重要手段.形式化建模需要领域知识和形式化知识的结合，由于形式化知识难以掌握，领域专家在建模整个过程中都需要形式化专家的帮助.为了解决这个问题，针对联锁系统的故障随机性、行为实时性、构件可重用的特点，提出设计联锁领域特定语言IS-SDL描述具体的联锁系统的参数，并基于随机混成自动机模板自动生成联锁系统的形式化模型，以进一步在此基础上进行安全分析.首先对联锁系统模型进行分析，根据不同案例设计其领域特定语言；其次，确定联锁系统的系统模型的模板，包括环境构件模板和控制器模板，并举例抽取其随机混成自动机模板；在模板基础上定义系统模型生成过程，让领域专家可以通过领域特定语言，输入参数自动生成具体的随机混成自动机系统模型；最后以某站联锁系统为例，展示了基于模板的具体系统模型的生成过程，并通过基于系统模型的事故预测分析，证明了该方法的可行性与有效性.     

基于Zoom-FFT技术的铁路移频信号检测系统设计

为精准检测轨道移频信号的特征参数值,实现列车通信数据的实时稳定传输,设计基于Zoom-FFT技术的铁路移频信号检测系统;以AD转换电路作为核心电子输出装置,借助DSP移频芯片、信号传感单元对于列车通信数据的聚拢调节作用,在LCD屏幕内生成即时性铁路移频信号显示文件,再联合微处理接收元件,实现对信号特征参量的精准获取,完成检测系统的硬件结构设计;在此基础上根据信号数据的瞬时输出频率,确定标准的模态移频函数,完成基于Zoom-FFT技术的铁路移频信号频率分析;设置数据采集、移频滤波、WIFI通信三类程序型算法,建立信号数据库与核心检测主机间的物理连接,实现系统检测软件及应用主程序建立,结合以上所有软、硬件执行结构,完成基于Zoom-FFT技术的铁路移频信号检测系统设计;对比实验结果显示,应用新型检测系统后,低频、高频轨道移频信号的检测精度均出现明显提升,解决了原有检测系统支持下,列车通信数据实时传输稳定性较差的问题。     

基于计算机联锁的铁路信号自动闭塞系统

针对我国传统的继电联锁方式的铁路信号自动闭塞系统,文章介绍了一种基于计算机联锁方式的改进方案。该方案不仅具有继电联锁方式的安全性和可靠性,还扩展了很多实用的功能;不仅兼容现有系统,还能适用于将来的新系统。文章还从系统结构和软件模型方面对这种方案的各种性能进行了分析。在该方案的基础上还可组建调度监督网络,提供很好的远程访问能力。     

基于Duffing振子的铁路轨道移频信号测量系统设计

铁路轨道作为移频信号的传输载体,其对于信号对象传输轨迹疏密度的辨别能力,决定了轨道体系对移频信号的测量准确性。为实现对信号对象传输频率的准确辨别,设计基于Duffing振子的铁路轨道移频信号测量系统。将电源模块输出的电量信号,按需分配至STM32F103 微处理器、移频信号辨别模块与DSP测量单元之中,完善各级应用部件之间的连接关系,实现铁路轨道移频信号测量系统的硬件方案设计。确定移频信号的Duffing振子描述条件,针对其定义形式,构造移频信号的相空间,完成对铁路轨道移频信号的提取。求解铁路轨道的Lyapunov指数,并构建移频信号的Duffing方程,确定混沌测量参数的取值范围,实现对铁路轨道移频信号的测量,联合各级应用部件,完成基于Duffing振子的铁路轨道移频信号测量系统设计。实验结果表明,上述系统测量所得信号传输轨迹疏密度与真实轨迹疏密度相似度较高,能够实现对铁路轨道移频信号的准确测量。     

铁路信号站场图形一致性检测的算法设计

分析了铁路信号计算机联锁系统中的站场拓扑图形生成机理问题,阐述了图形设备单元的设计过程及其与道岔、信号机及区段数据基的实时对应关系;提出了图形绘制更新流程和图形一致性检测程序流程,对绘图类与联锁程序和通信接口的关系进行了表述,并给出了一种基于代价有向站场拓扑图的k步扩散进路搜索算法;通过C++编程实现了上述图形检测生成算法,并在工程项目中进行了应用,最后对具体的实例进行了算法仿真模拟。     

Railway-controller-perceived competence in incidents and accidents

Railway controllers play a pivotal role in service recovery of normal rail system operations when incidents and accidents occur. Those in this position must have sufficient competence to overcome task difficulties caused by accident uncertainties. This study adopts Taiwan's railway system as a case study to diagnose railway-controller-perceived competence when facing diverse tasks during incidents and accidents that are derived from a proposed conceptual model. Railway-controller-perceived competence is measured using the Rasch model. Analytical results indicate that working with an external rescue agency handling a rescue operation, explanations to the public, and communication with an external rescue agency are considered the most troublesome tasks. Additionally, railway-controller-perceived competence differs based on the work experience. This information will prove useful for rail system operators and government regulators when designing and regulating railway controller competence management systems.

Statement of Relevance: This study presents a systematic approach for examining the gap between railway-controller-perceived competence and task difficulties associated with incidents and accidents. The relevance of findings encompasses the effects of transportation ergonomics and railway issues on the problem-solving competence and decision-making skills of railway controllers, and the competence management system.     

A computer algebra approach to the design of routes and the study of their compatibility in a railway interlocking

A railway interlocking is a device that supervises train operation (signaling and position of switches) authorization and prevents conflicting actions from being authorized. An expert system for route selection in a railway interlocking is presented, that is independent of the station topology. It is Maple-based and uses lists (it performs a kind of adapted knowledge extraction and verification). Given the track arrangement, it can determine all routes that begin in a given section and all routes that are an extension of a given route (in both cases it is possible to ask what routes end at a given section). Routes can be classified according to number of sections and, given a time estimate for crossing each section, timing for each route can be calculated. Therefore, the program makes it possible to optimize the route according to different criteria. Moreover, thanks to the chosen data structure, decision making on the compatibility of a proposed route is straightforward.     

A graph theory-based approach to route location in railway interlocking

The location and verification of routes is an important component of railway interlocking logic design. The interlocking routes are typically listed manually by experienced signaling engineers, and this task is both time consuming and expensive. In this paper, an automatic, graph theory-based approach to route location and verification is presented. In this new approach, a component-based model is used to represent the topology of the station layout, and a modified matrix algorithm based on graph theory is used to locate all of the routes in a given station. This algorithm exhibits superior performance in the location and verification of routes and is universally applicable, irrespective of the station layout. When a station is modified, the designers can simply update the topological data for the station, and the new route information can be obtained automatically.     

一种新型高压不对称脉冲轨道电路接收器的研制

轨道电路是铁路信号系统中重要的设备之一,轨道电路的故障将影响行车安全。分路不良是其常见的故障之一,高压不对称脉冲轨道电路是解决分路不良的有效手段,然而当前的设备存在线路衰减、需要补偿、费用昂贵等缺点。提出了一种基于网络化的轨道电路接收器方案,直接在室外对高压不对称脉冲的特征参数进行提取,并通过CAN总线网络传输到室内,现场测试数据表明,系统测试精度达到设计要求,能可靠替代原接收器工作。     

VacChain: A Blockchain-Based EMR System to Manage Child Vaccination Records

The digitalization of healthcare-related information service systems has become a trend across the world. However, several crucial services are still provided manually due to a lack of trust in digital solutions. One such service is keeping records of children’s vaccination, which still relies on a paper-based file system in most parts of the world. This approach causes serious data integrity problems. Recently, healthcare has become a potential application area of the blockchain, as it can preserve and protect highly sensitive private medical records while sharing these records in a decentralized manner without losing personal ownership. Therefore, we propose a new digital model to track a child’s vaccination records using blockchain. In particular, this proposed application helps improve the vaccination record-keeping process by ensuring the integrity of the preserved data in a more secure way. In an emerging pandemic situation, our approach can be extended to manage the overall vaccination process effectively.