Extending Petri net to reduce control strategies of railway interlocking system

In our previous articles we gave step by step refinement process towards the development of safety properties of moving block interlocking system (MBRIS). The refinement process started from abstraction to fuzzy based safety properties using Z and then fuzzy multi agent specification language. However, one dimensional control of train passing through a switch and level crossing were not discussed. This paper reduces the existing two dimensional controls along the switch and level crossing to one dimensional for shifting it to a train only. For example, in the existing model the train movement along components switches and level crossings depends on both the train and components control. Whereas, in one dimensional control train is the only authority to control a switch and level crossing required for its desired operation. For this reduction, concurrent and mobile agent concepts are required. Therefore, we integrate mobile agent concepts with Petri nets to develop the mobile Petri net (MPN) a new class of PNs. This supports both mobility and concurrency. Further, we prove that the collection of different MPNs in a connected network is a PN. This proof allowed us to use the properties of PN to verify the system. Finally, we use MPN to model the safety properties of MBRIS along the switch and level crossing. This provides one dimensional control to a train along a switch and level crossing which increases the safety of the railway interlocking system. Moreover, we use reachability graph (RG) to verify the switch and level crossing models.     

基于活性顺序图的形式化验证方法及工具研究

近年来,形式化验证方法在软件开发过程的作用越来越大。如何充分利用形式化验证方法提高软件系统的可靠性已成为软件开发者及使用者主要关注的问题。总结了近年来基于活性顺序图的形式化验证方法的研究进展,首先介绍活性顺序图的语言及其表达能力与复杂性,然后深入分析现有的基于活性顺序图的形式化验证的关键技术及其典型应用,最后实现一种基于活性顺序图的运行时验证工具,实验证明使用本验证工具进行形式化验证的可行性。     

软件实现模糊评判法对特高含水期油田开发效果评价

针对目前油藏特高含水期水驱开发效果多项评价指标相互独立、关联性差的特点,编制软件实现各项评价指标及分级标准临界值的动态输入,后台利用模糊评判法将油藏开发状况因素中的一些定性描述定量化,最终以数值的形式判断开发效果并呈现在人机交互界面.将以杏一~三区西部乙块地质特征和油田开发实际数据资料为基础验证软件运行结果,评价符合开发实际.使用此软件评价方便简单,结果全面可靠,同时由于数据录入的动态性,可应用于同类型的其他油藏.     

Diamond软件在晶体对称性教学中的应用-32点群晶体模型库的建立

介绍了用Diamond软件构造32点群晶体结构模型的方法,给出了建立晶体结构模型的具体参数.利用此模型有助于加深学生对点群及其与晶体结构关系的理解.     

ICPS-1000Ⅱ型等离子光谱仪控制系统的升级更新

通过对岛津ICPS-1000Ⅱ型等离子体光谱仪控制系统的升级更新,使用PC系列微机,插入IEEE-488并行通讯接口卡,替代原三菱MULT 116计算机,实现了对ICPS-1000Ⅱ光谱仪主机的控制,将原软件移植成功。进一步开发了该仪器的功能,使其维修、维护和应用变得方便、快捷。     

Design and use of reference data sets for testing scientific software

A general methodology for evaluating the accuracy of the results produced by scientific software has been developed at the National Physical Laboratory. The basis of the approach is the design and use of reference data sets and corresponding reference results to undertake black-box testing.

The approach enables reference data sets and results to be generated in a manner consistent with the functional specification of the problem addressed by the software. The results returned by the software for the reference data are compared objectively with the reference results. Quality metrics are used for this purpose that account for the key aspects of the problem.

In this paper it is shown how reference data sets can be designed for testing software implementations of solutions to a broad class of problems arising throughout science. It is shown how these data sets can be used in practice and how the results provided by software under test can properly be compared with reference results. The approach is illustrated with three examples: (i) mean and standard deviation, (ii) straight-line fitting, and (iii) principal components analysis. Software for such problems is used routinely in many fields, including optical spectrometry.     

Off-road tyre modelling II: effect of camber on tyre performance

The problem of off-road vehicle tyre-terrain interaction is that it is difficult to model accurately. For an off-road vehicle over medium to firm terrain, the tyre load may be entirely supported by the tips of the lugs, or with a minimum carcass contact with the terrain. In this case, the effect of the lugs should be taken into consideration. The forces at the interface between lugged tyre and the soil, including normal and shear stresses, are discussed in this paper. The multi-spoke tyre model was developed to study the effect of tyre lugs on the forces between tyre and terrain and it has been extended to predict the tyre forces and moments in the case of combined lateral and longitudinal slip for a cambered tyre. The influence of slip angle, camber angle and soil hardness on off-road tyre performance has been investigated. A computer program was developed using MATLAB software. The results were derived as tyre forces and moments in the three directions along the tyre contact length. A comparison between the results of the multi-spoke tyre model of a smooth off-road tyre and an off-road tyre with straight lugs, in the cambered case, has been made. The results indicated that slip angle, camber angle and soil characteristics have a strong effect on off-road tyre performance. The modified mathematical model results help the off-road tyre engineering designers to predict accurate values of tyre forces and moments in this complex case.