The Petri Net Kernel An infrastructure for building Petri net tools

The Petri Net Kernel is an infrastructure for building Petri net tools. It relieves the programmer of a Petri net tool from implementing standard operations on Petri nets and a graphical user interface. In this paper, we discuss the motivation, the concepts, and the implementation of the Petri Net Kernel. Published online: 25 July 2001     

One year older, but not necessarily wiser: an evaluation of homepage accessibility problems over time

A large number of users with disabilities use assistive technology devices to browse the web. However, the use of assistive technologies can only be successful when the web sites are developed in such a way that they are compatible with such devices. Guidelines exist for creating accessible web sites. However, they are seldom followed, and current levels of web accessibility are low. Therefore, the question arises as to which is the major cause of inaccessibility, and how accessibility features of web sites evolve over time. A set of 50 web sites has been studied over time to determine if accessibility improves or declines. This research-in-progress paper presents a comparison of the results obtained in 2002 and 2003. Such a comparison leads to the conclusion that, in the time period of 1 year, the 50 web sites have actually become more inaccessible. Implications for developers, webmasters, and educators are also discussed in the paper.

Evolving Object-Oriented Designs with Refactorings

Refactorings are behavior-preserving program transformations that automate design evolution in object-oriented applications. Three kinds of design evolution are: schema transformations, design pattern microarchitectures, and the hot-spot-driven-approach. This research shows that all three are automatable with refactorings. A comprehensive list of refactorings for design evolution is provided and an analysis of supported schema transformations, design patterns, and hot-spot meta patterns is presented. Further, we evaluate whether refactoring technology can be transferred to the mainstream by restructuring non-trivial C++ applications. The applications that we examine were evolved manually by software engineers. We show that an equivalent evolution could be reproduced significantly faster and cheaper by applying a handful of general-purpose refactorings. In one application, over 14K lines of code were transformed automatically that otherwise would have been coded by hand. Our experiments identify benefits, limitations, and topics of further research related to the transfer of refactoring technology to a production environment.     

CC-Linux集成开发环境的设计与实现

根据嵌入式系统的开发特点,给出了嵌入式Linux的集成开发环境的设计与实现,并针对其中的ETK环境给出了关键技术的详细介绍。     

快速工程可视化应用软件开发研究

Windows使计算机的使用变得非常容易而有趣 ,但其应用程序的开发越来越复杂 ,为解决这一问题 ,特撰此文 ,详细论述了开发工程可视化应用程序的不同方法 ,此开发工具乃科研、工程人员的最佳选择。     

国外航空电子系统嵌入式在线监测技术

在分析国外航空电子系统嵌入式在线监测体系架构和五级监测解决方案的基础上,介绍了国外嵌入式在线监测技术、标准和开发验证工具的发展情况,提出了全机级嵌入式在线监测体系架构、嵌入式专用监控模块研制、嵌入式在线监测系统的仿真验证平台的构建和标准化建设等方面开展工作的建议,希望能够为未来我国航空电子系统嵌入式在线监测技术的发展起到一定的借鉴和指导作用。     

数字仿真技术在电力系统中的应用及常用的几种数字仿真工具

介绍了电力系统数字仿真技术的分类、特点及其在电力系统中的应用,并介绍了几种当前较为流行的数字仿真工具及其特点,最后对电力系统数字仿真技术的发展进行了展望。     

Thixoforging of Steel Using Ceramic Tool Materials

Today thixoforming processes are mainly established in the production of parts made of aluminium alloys. Compared to high melting alloys the process temperature is low and thus the process is easier to handle. Because of process temperatures up to 1470°C thixoforming of steels demands a sophisticated process control and adapted tool materials. In this field there is still a large need for research. This paper deals with experiences made at the IFUM concerning the thixoforging of steel. The use of ceramic tool materials for thixoforging of steel is presented. For this purpose hybrid dies where a ceramic insert is prestressed with a hot working steel shrink ring as well as different stamp geometries were developed and built up. Different ceramic materials from Si₃N₄ to ZrSiO₄ were tested and evaluated. To prevent an unwanted cooling and oxidation of the slug during its transfer, the transfer is carried out encapsulated in high temperature resistant crucibles that can provide a protective atmosphere. The suitability (e.g. thermo shock resistance) of different materials for the use as transport crucibles was also subject of this research work. The forming experiments were carried out with the institute's hydraulic press. The process logic controller of this press offers the appropriate flexibility and various control modes needed for a sophisticated and reproducible filling of the die. In this way the die filling process of different steels can be tested.     

空间曲面零件的量具设计

对于批量生产的汽车车身零件的空间曲面和空间孔，需要用专用量具进行测量。文章就测量要素和测量基准的确定；检测方式；加工误差与鉴定基准等量具设计相关问题进行了论述。