In the development of embedded systems, safety and reliability are important quality characteristics. Fault tree analysis is often used to determine these characteristics. Fault tree analyses are usually performed manually. Taking into account the high complexity of today's technical systems this is in many cases not possible within the limits of existing time and budget constraints. Furthermore, completeness and precision of the results are neither guaranteed nor systematically provable. The automatic generation of generalized fault trees permits saving time and effort and increases the quality of the results. Completeness, correctness, and consistency of the generated fault trees are guaranteed. We have developed, apart from other approaches, a fault tree generation tool for electronic circuits that generates fault trees based on the standardized electronic design interchange format (EDIF). This tool has been used e.g., to analyze failure situations in industrial automation applications. As automatic fault tree generation makes possible analyzing even very large systems, existing algorithms for calculation of reliability figures needed considerable improvement regarding performance. We implemented a BDD-based algorithm to solve that problem. Furthermore, our tools have been verified by a Back-to-back test to support use in certification of safety critical systems.
Public Query Language (PQL) is one of the query syntax for database, categorized as highly user friendly compared to the 4-th generation language. From point of view of user, there is only one virtual relation or flat file in database. One of the alternative explored for execution of PQL : using SQL-based DBMS as an engine. For this alternative, PQL is converted first to SQL syntax. Conversion from PQL to SQL is based on exploration of real relations (may be more than 1) involved to answer the query, using primary-key and join-path as main factors of exploration. In consequence, every attribut mention in PQL must be chosen from relation stand for "entity" or as primary-key. Join the relations is performed and based on primary-key, and using shortest path. Doing so, there are 2 principal points : identify relation involved, and joint the relations using primary-key as maximum.
This work presents the WUC system definition. WUC system is an integrated tools set for workflow developing. WUC system contains tools for helping in workflows construction process, including specification, analysis and verification. The objective of this work is to provide a tool that facilitates the workflows production.Our interest is to facilitate processes definition methods and notations for helping to visualize the processes graphically and to incorporate formal specifications in its definition, in order to be able to prove basic properties (ie. no deadlock) and to be able to guarantee the process appropriate operation.WUC system is conceived as the integration of a group of interactive subsystems. They communicate to each other and they share a friendly interface. The system implementation is carried out on a platform based on microcomputers with Pentium processors and Windows NT as operating system, using Java as programming language.
Workflow management systems are gaining importance as an infrastructure for effectively managing business processes in several application domains. A workflow can typically be specified as a set of tasks, and coordinating relationships among these tasks. In an earlier work [1], Atluri et al. proposed an approach that can automatically redesign a workflow in such a way that it minimizes the number of communications and interference between sites. In this paper, we summarize the effectiveness of the proposed techniques (split-task and compensate-task) in reducing the inter-site communications and improving the concurrency within a workflow. Towards this end, we develop and evaluate several performance metrics. The results clearly indicate the efficacy of the split-task and the compensate-task approaches in achieving the desired objectives.
This paper is concerned with network security, and proposes a new network-unauthorized access analysis method. This method allows Multi Layer Monitoring (ML-Mon) covering OSI-7-layer model. ML-Mon function consists of various newly-developed modules such as: Cracking Analysis Protocol Stack (CAPS), optimized for analyzing unauthorized access on the network; Application Layer Level session Re-assemble function (ALLR); and CAPS-Application Program Interface (CAPS-API). The innovative feature of ML-Mon are 1) existing network protocols and hardware remain unchanged, and 2) enables unauthorized access analysis up to the application level. This paper describes in detail CAPS and software package called "Cracking Analyzer" that implements CAPS. CAPS is the key technology of ML-Mon. CAPS is a generalized protocol stack. CAPS can handle third party communications, pick out any protocol stack layer's data. Cracking Analyzer is a software that implements CAPS. Cracking Analyzer's Application Program Interface (API) is very similar to standard protocol stack's one. Using the API, many cracking analysis program is written with very a few program steps, and the program can analyze up to application layer level cracking.
Over the past several decades, corporations have invested trillions of dollars in implementing EDI systems with their major trading partners using traditional EDI methods such as ANSI ASC X12 and UN/EDIFACT. While this investment has yielded significant improvements in efficiency and savings, the savings have not been more than 20% of the potential savings, because traditional EDI has been too complicated and expensive for most Small and Medium size Enterprises (SMEs). As a result, many methods for involving SMEs in EDI have been invented. This paper briefly describes and compares four major of these methods. It shows that XML/EDI method is a more flexible and cost effective solution for business data interchange that can play a complementary role in a peaceful co-existence with traditional EDI.
In this paper the most relevant works related to software process are reviewed. Software process modelling tries to capture the main characteristics of the set of activities performed to obtain a software product, and a variety of models have been created for this purpose. A process model can be used to define a recommended software process. This paper deals with the prescriptive software process modelling and the most relevant results of this approach is presented.
This research proposes a method to analyze relation between visitors' impressions and design of B2C web page. The model of design factors and impression factors was used to investigate the causal relation between visitors' impressions and design of B2C web page. In empirical study, two questionnaire investigations were conducted, in which the first one was done to constrict important factors of visitors' impressions and B2C web page. The second investigation was aiming at visitors' impressions to improve design of B2C web pages that consist of eight design factors in an interacting experiment. The evaluation values of impressions items were collected in self-report questionnaires. Sign test of the results of investigations shows significant difference of visitors' impressions corresponding to the alteration of design factors applied in design of B2C web pages.
Current geographical information systems (GIS) handle large amounts of geographical data stored usually in relational databases. Database vendors developed special database plug-ins in order to make retrieval of geographical data more efficient. Basically, they implement spatial indexing techniques aimed at speeding-up spatial query processing. This approach is suitable for those spatial queries, which select objects in certain user-defined area. Similarly as on-line transaction processing (OLTP) systems evolved into on-line analytical processing (OLAP) systems for supporting more complicated analytical tasks, similar evolution can be expected in the context of geographical information analytical processing. This paper describes the GOLAP system consisting of a commercial OLAP system enriched with a spatial index. Experiments comparing efficiency of original OLAP and the extended one are presented.
1 R. GIRARDI, "An analysis of the contributions of the agent paradigm for the development of complex systems", In: JOINT MEETING OF THE 5TH WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS (SCI 2001) AND THE 7TH INTERNATIONAL CONFERENCE ON INFORMATION SYSTEMS ANALYSIS AND SYNTHESIS (ISAS 2001), Orlando, Florida. 2001. Abstract This article analyzes main concepts of the agent-based development paradigm and its basic mechanisms to support the development of complex systems: decomposition, abstraction and flexible interactions.
Information system technical performance depends upon the underlying information infrastructure. Information engineering, information security, data streams, networks, and quality of service are portions of the infrastructure comprising an information system solution. Maintaining the United States Navy information superiority over adversaries necessitates functions including, access to digital libraries, data fusion, collaborative filtering, event detection and tracking. Change's in threats and operational environment require an adaptive information system interface, new queries over time, and reordering of doctrine. With a system engineering approach employing earned value management, technical performance parameters are defined for use in the specification, development monitoring, and verification of systems. This paper defines essential technical performance parameters for information system development in a modem system-engineering framework.
This paper describes a real-time scheduling problem of the mixture of periodic and aperiodic tasks. This mixture is scheduled by a combination of algorithms with fixed priorities. Periodic and aperiodic workload significantly determine the scheduling properties. The developed software tool enables simulation and evaluation of implemented scheduling algorithms. In the dependency of the workload and the defined simulation conditions, mean aperiodic response time, number of tasks with missed deadlines and resource utilization are observed. The obtained results enable a simple mutual comparison of graphical results, selection of corresponding algorithms or a later on-line implementation of algorithms in the computer system.
To ensure the consistency of database subsystems involved in wireless communication systems, appropriate scheduled maintenance policies are necessary. However, the short-persistence of most of the data stored in the database and the highly dynamic evolution of the environmental conditions, which characterize such target systems, pose relevant issues in devising efficient maintenance policies. Aiming at deriving optimal maintenance strategies, this paper tackles the problem in two steps. First, a method is outlined to identify the most rewarding choice of audits frequency and combinations, given a setting for relevant parameters involved in the database of wireless communication systems (e.g., mean number of user calls and data corruption rates). Second, a learning approach is presented to dynamically adapt the maintenance policy at varying database and environmental parameter values leading to select, in each time period, the optimal maintenance policy.
Reference LEM-CONF-2001-005Afficher la publication dans Web of Science Notice creee le 2004-09-07, modifiee le 2017-05-12
Content Management Systems are a means to store information independently from its later presentation on a user interface. To display content on different kinds of output devices (e.g. 17" screens, PDAs, and mobile phones) an appropriate user interface is necessary. Today, each user interface has to be programmed separately according to the representation capabilities of the output device. This means if the output devices are becoming more advanced, e.g. are colored or have higher resolutions, the interface parameters will change. This results in user interfaces having to be amended or sometimes completely rewritten. The same applies when additional devices need to be supported, and they subsequently require new user interfaces to be built from scratch. Obviously, this is time-consuming and costly. A similar problem exists for the input of data. Possible input devices for text are a computer keyboard, an OCR (optic:71 character recognition) system, a speech recognition system, or a handwriting tablet. In this paper, we present a practical process using XML as the basic technology to derive any kind of user interface from an abstract description.
The authors have been engaged in reconstruction of the school information system on the campus LAN of Kyushu institute of Technology since 1993. Main ideas of the reconstruction, as well as three stages in the process of reconstruction of the information system, are reported in this paper.
Today's web-based information systems usually employ database systems to store their content, forming the basis for web page construction. Generating web pages on request, especially in peak times, however, can lead to severe performance problems. Thus, our approach of "self maintaining" web pages suggests to materialize web pages outside the database and to update them every time the underlying content changes. Maintaining the mapping knowledge between database content and web pages in an efficient way, however, represents a major challenge. Our approach of self-maintaining web pages tackles this problem by means of different concepts. First, instead of allocating individual content fragments to single web pages, parameterized content fragments are allocated to web page classes. Second, the Extensible Markup Language (XML) is used as an intermediate layer between the database content and the final web pages, thus allowing to propagate updates only to those elements which are actually affected. Third, a meta schema allows to reify the mapping knowledge, thus enhancing maintainability and changeability. This paper focuses on the meta schema, representing a core component of our approach.
