Debugging and Run-time Monitoring of Active Rules

Especially during the design and tuning of active rules, it is possible that rule execution enters an endless loop, where rules cascade by triggering each other indefinitely, so that their processing does not terminate. Commercial systems detect this situation in a simple way, by keeping counters on the number or depth of cascading rules, and suspending an execution when the counters exceed given thresholds. However, the setting of these counters is quite critical: too low thresholds may cause the halting of rule processing in absence of loops, too high thresholds may reveal a loop only after an expensive processing. In this paper, we propose a technique for revealing loops, which is based on recognizing that a given situation has already occurred in the past and therefore will occur an infinite number of times in the future. We exploit this property to develop cycle monitors, which check at run time that critical rule sequences, detected at compile time, do not repeat forever. We describe the run-time monitoring environment of Chimera, an active DBMS prototype currently under development at the Politecnico di Milano, and we illustrate with a concrete applicative example the results obtained with the cycle monitoring technique.     

Tool support for the design and management of context models

A central task in the development of context-aware applications is the modeling and management of complex context information. In this paper, we present the NexusEditor, which can ease this task by providing a graphical user interface to design schemas for spatial and technical context models, interactively create queries, send them to a server and visualize the results. One main contribution is to show how schema awareness can improve such a tool: The NexusEditor dynamically parses the underlying data model and provides additional syntactic checks, semantic checks, and short-cuts based on the schema information. Furthermore, the tool helps to design new schema definitions based on the existing ones, which is crucial for an iterative and user-centric development of context-aware applications. Finally, it provides interfaces to existing information spaces and visualization tools for spatial data like GoogleEarth.     

主动数据库及在DSS中的应用研究

主动数据库是数据库技术中一个活跃的研究领域，它是在传统数据库的基础上，结合人工智能和面向对象技术提出的，其主动性功能正在各种应用中发挥越来越大的作用。主动数据库强调数据库反应能力上具有主动性、快速性和智能化的特性，而决策支持系统要求数据库具有很强的数据预处理和数据分析能力，将主动数据库应用于决策支持系统中，一定会使决策支持系统具有更强的优越性，从而更好地发挥决策支持系统辅助决策的作用，以满足各种层次、各种类型、不同决策者的决策过程对数据的要求。     

雷达装备综合保障辅助决策系统开发

随着装备的现代化发展,装备保障已成为战斗力的重要组成部分,它逐渐与作战性能居于同等重要的地位,如何及时、正确、有效地进行决策部署成为现代装备工作的重要目标.本文从雷达装备保障的实际需要出发,开发设计了此决策支持系统,很好地实现了其预定功能目标,并为决策支持系统在更多领域的应用提供了参考.     

雷达装备综合保障辅助决策系统开发

随着装备的现代化发展,装备保障已成为战斗力的重要组成部分,它逐渐与作战性能居于同等重要的地位,如何及时、正确、有效地进行决策部署成为现代装备工作的重要目标。本文从雷达装备保障的实际需要出发,开发设计了此决策支持系统,很好地实现了其预定功能目标,并为决策支持系统在更多领域的应用提供了参考。     

Using an entity model to drive physical database design

Logical relational database design, because of its implementation-independent nature, has been successfully formalized. Physical relational database design, because of its implementation-dependent nature, has remained largely unformalized and disconnected, not only from logical design but also from conceptual database design. The paper suggests a model for the physical design process that has proven useful in a number of practical development projects. The model demonstrates that a seamless join between conceptual, logical and physical design work is feasible. It illustrates how the process of annotating a conceptual model with physical detail provides a useful framework for driving the process of physical relational database design.     

S4W: a problem‐solving environment for wireless system design

This work describes the Site‐Specific System Simulator for Wireless System Design (S⁴W), a problem‐solving environment (PSE) that integrates visualization and computational tools with a high‐level graphical user interface. S⁴W improves the ability of wireless system engineers to design an indoor wireless system by encouraging them to think in terms of designing the system for optimal performance. Issues of computation management, data management, and location of resources are hidden from the user. The complex nature of data sets in the domain of wireless simulations calls for a customized set of visualization tools. Therefore, a number of ad hoc visualizations were developed for S⁴W. A study comparing the integrated system with an earlier, unintegrated version is presented. This helps to demonstrate the productivity gains that a PSE provides. Copyright © 2007 John Wiley & Sons, Ltd.     

Knowledge-based design environment for primary shaped micro parts

This contribution describes a prototypical knowledge-based design environment predominantly concentrating on the production-relevant design of micro parts. In this environment a computer-aided knowledge base is linked with a design system (CAD-system). In contrast to a complete knowledge-based design, i. e. modelling a part by the rule-based connection of distinct basic objects or features (which is a matter of structured combination rather than creative designing) the prototype presented promzotes conventional practical design. The designed part is subsequently checked on the basis of parameters derived from the geometry of said part.This paper was presented at the Fifth International Workshop on High Aspect Ratio Microstructure Technology HARMST 2003 in June 2003. The work is part of the DFG (Deutsche Forschungsgemeinschaft) funded collaborative research center 499 Development, production and quality assurance of primary shaped micro components from metallic and ceramic materials     

A design environment for laminated fiber-reinforced thick composite materials

The research described herein concerns the integration of several components of engineering software using a relational database. More specifically, a conceptual finite element material preprocessing system for laminated fiber-reinforced thick composite materials is studied. In this computer-aided analysis (CAA) system, a materials database is integrated with several software components, including commercially available finite element analysis (FEA) programs and preprocessors, and tools for the design of laminated composite materials. The system focuses on assembling, manipulating and using composite materials data, resulting in the transfer of 2-D and 3-D composite materials property data into a finite element analysis program. The system is life-cycle in nature, supporting a composite through testing, analysis and design. it offers great versatility in its ability to use raw ply data from any source, design layups, and generate laminate properties and FEA materials data files. Despite the fact that such integrated systems are not new in many domains, they have not been successfully introduced to the redlm of composite materials analysis and design. This outcome is due largely to the nature of the materials themselves and the overhead they bring to the development of a successful life-cycle model.     

A formal semantics for an active functional DBPL

We describe how the functional database programming language PFL is extended with an active component without compromising either its declarative semantics or its syntax. We give a formal specification of the active component using PFL itself, including event specification and detection, parameter-binding, reaction scheduling and abort handling. We describe how a user-specified function can be cast as a primitive event, and discuss the expressiveness of events and the optimisation of event detection.     

动态环境下的主动蠕虫攻击分析

鉴于当前很少有传播模型充分考虑到P2P节点动态特征对主动蠕虫攻击的影响, 提出两个动态环境下的主动蠕虫传播模型。分析了主动蠕虫两种常见的攻击方式, 给出了相应攻击背景下的节点状态转换过程, 在综合考虑P2P节点动态特征的基础上提出了两种主动蠕虫传播模型, 并对所提出的模型进行了数值分析, 探讨动态环境下影响主动蠕虫传播速度的关键因素。实验结果表明, 通过提高P2P节点的离线率和免疫力可以有效地抑制主动蠕虫对P2P网络的攻击。     

Query facility for synthesis-based prototype universal relation (SPUR) system

Recently, considerable interest has been shown in the automation of database design. The paper discusses the query facility for an experimental prototype of a database management system (the SPUR system) based on the universal relation concept, which removes some logical database design details from the human designer. The basic motivation for the study as a whole is to make databases easier to develop and use. The query language of the SPUR system is described and its power and correctness are explored through the use of case studies. The feasibility of implementing such a query language is established, although the user, perhaps not an end-user in this case, needs to have a good understanding of database terminology to use the system effectively.     

集成虚拟现实环境在工程设计分析中的应用 *

虚拟现实技术在工程设计与分析上有很大的应用潜力。可是 ,虚拟环境的创建时间长、成本高,极大地限制了虚拟现实技术在工程上的应用。为此 ,提出了虚拟现实脚本生成器的概念,将虚拟现实技术与过程的设计、分析集成化,创造性地提出了一种自上而下的设计方法———VR-IEDA,以便高效、快速地创建虚拟原型,提高计算机虚拟复杂系统工程的性价比。在 VR-IEDA中复杂系统的结构和行为被计算机捕捉并自动生成可执行的 VR仿真代码 ,从而减少了创建虚拟环境的时间,便利了基于仿真的过程分析和设计。最后 ,以武器系统的维修过程为     

面向机床产品的协同设计支持环境的研究

对机床产品协同设计过程及其特点进行研究，采用UML统一建模语言中的泳道图表示机床协同设计过程，提出了面向机床产品的协同设计支持环境的层次结构，该协同设计支持环境主要由3个方面的内容组成：对机床产品设计开发活动的支持、对设计活动单元组织和管理的支持、对设计活动单元间协同的支持。采用分布式为主、集中式为辅的方式，建立了面向机床产品的协同设计支持环境的体系结构，并对实现该体系结构的任务规划、协同约束模型、冲突消解等关键技术进行了研究。在此基础上，开发了面向机床产品的协同设计支持环境的原型系统。     

Database design practices for inverted files

Database research literature has proposed many procedures, both manual and automated, for database design; selection of secondary indexes for inverted file type database management systems (DBMS) has been repeatedly addressed. The empirical study reported here indicates that practical inverted file design has been relatively unaffected by this research.This paper characterizes the actual database design process used at inverted file DBMS installations along such dimension as: types of secondary keys constructed, the individuals who make index design decisions, the decisions that are changed (and when) after the initial database implementation, the factors that are considered in indexing decisions, and the literature which is used in the process. The study shows that key selection (as one example of a design decision) is addressed by ad hoc procedures and well conceived procedures are not used. Further, the results indicate that database design is dominated by users and systems analysts, indexes are frequently changed and a wide range of database performance and convenience factors are influential in practice. The paper concludes with some recommendations for database design support tools.     

XML中的主动规则的模型及其可终止性分析

在对XML数据模型主动机制研究的基础上,结合规则实例提出了一种新的分析规则终止性的静态判定算法。此算法基于触发环的概念,首先对触发环中每一个被修改的节点产生一个递归等式,然后通过展开递归等式并检验其可满足性,就可以分析规则集的可终止性,这样不仅可以得到更高的精确度及更小的复杂度,而且可以得到有效的判定主动规则可终止性的条件。     

Participatory design in interactive media design education for the solution of unfamiliar design problems: a case study on a disabling environment and an emerging technology

This paper investigates the effectiveness of participatory design study in rendering the students' capability of producing innovative design solutions to problems with uncertainties with which the students have no prior experience. At the project, the students were given a case to work on augmented reality technology with which they had no previous experience and design a tactical interface for sailing boats, a field they had no competence in. While the students were asked to develop proposals for this design problem with which they were inexperienced, a two-stage study was conducted to enable them to produce ideas on the topic. This paper discusses the impacts of such a participatory method in terms of design education. At the end of our study, it was observed that the students were positively influenced by the process in which they worked collaboratively with an expert user group.     

Database design with user-definable modelling concepts

Modelling is an integral part of engineering processes. Consequently, database design for engineering applications should take into account the modelling concepts used by engineers. On the other hand, these applications exhibit a wide diversity of modelling concepts. Rather than consolidating these into one single semantic data model one should aim for correspondingly specialized semantic models. This paper takes a constructive approach to developing such specialized models by proposing an Extensible Semantic Model (ESM) as the basis for declaring specialized semantic data models. The paper introduces a computerized environment for database design based on an ESM, and discusses the consequences of the ESM for a number of design tools: the need for a formal definition of the notion of modelling concept in order to have reliable and precise foundation for the extensions, declarative techniques for quickly introducing graphical representations for new concepts and for using them during schema design, conceptual-level test data generation for a designer-oriented evaluation of designs, and optimization techniques to control the wide latitude in mapping a conceptual schema to a logical schema. First experiences seem to point to considerable productivity gains during database design.