异构环境中基于特征关系的产品建模方法研究

基于特征的产品数据交换的完整性、一致性是异构集成环境下亟待解决的一个关键问题。该文在给出异构集成交换平台模型的基础上,提出了一种建立在平台上的基于特征关系的产品建模方法。该文试图从较高的层面上解决异构环境下基于特征的产品信息交换问题,以避免异构系统间的数据差异。该文在给出产品的交换平台模型的基础上,研究了基于特征关系的产品数据模型。最后分析了该模型的优点与尚需改进的地方。     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

基于WS-security的数据安全交换

分析了协同商务中数据交换的必要性，介绍了WS-Security技术规范的特点．论述了WS-Security技术解决数据安全交换的可行性和有效性。结合汽车产业链协同商务平台与汽车制造厂内部系统进行安全数据交换的开发实践．使用WSE工具实现数据安全交换，并给出了核心代码和运行实例。     

Managing the exchange of engineering product data to support through life ship design

An approach for managing the exchange of engineering product data between geographically distributed designers and analysts using a heterogeneous tool set for the through-life design of a ship is described. The approach was developed within a pan-European maritime project called VRShips-ROPAX 2000 that demonstrated how information technology could be integrated into the design process. This paper describes the development of a common model containing neutral ship product data through a bottom-up consideration of the requirements of the tools to be integrated, as well as a top-down consideration of the data requirements for through life design. This common model was supported within an Integrated Design Environment (IDE) that co-ordinated design activity distributed across Europe. The IDE ensured that the users were provided with the right data in the right form at the right time to do the right task, i.e., that the design activity was timely and appropriate. The strengths and weaknesses of the approach are highlighted.     

基于特征的CAD数据交换方法研究

分析了现有产品数据交换方法的基本特点并指出其不足之处,提出了一种基于特征的CAD数据交换方法,这种以定义造型功能映射集合为基础的新方法实现了不同CAD系统之间高效的数据交换,可保存高层设计意图。在Inventor和SolidWorks上初步实现了拉伸、旋转、扫描、圆角等几种特征数据交换,验证了方法的可行性。     

基于Internet的协同产品开发中基于Agent的工作流管理系统框架

基于Internet实现协同产品开发是虚拟制造技术和并行工程思想的融合,而实现它需要一个计算机系统提供有效的管理和支持。文章提出了一个新的框架,在分布式对象技术的基础上,充分发挥工作流技术在任务管理方面的优势和代理技术在知识表达、事务处理、智能性能方面的优势,以代理技术为框架基础,以工作流技术为核心,将这两种技术进行有机结合,使得工作流管理系统能够在Internet的环境下透明地管理协同产品开发中的工作流、资源和数据,从而达到支持协同产品开发的目的。     

An empirical framework for evaluating interoperability of data exchange standards based on their actual usage: A case study on XLIFF

Data exchange formats play a prominent role in facilitating interoperability. Standardization of data exchange formats is therefore extremely important. In this paper, we present two contributions: an empirical framework called XML-DIUE, for evaluating data exchange format standards in terms of their usage and an illustration of this framework, demonstrating its ability to inform on these standards from their usage in practice. This illustration is derived from the localization domain and focuses on identifying interoperability issues associated with the usage of XML Localization Interchange File Format (XLIFF), an open standard data exchange format.The initial results from this illustrative XLIFF study suggest the utility of the XML-DIUE approach. Specifically they suggest that there is prevalent ambiguity in the standard's usage, and that there are validation errors across 85% of the XLIFF files studied. The study also suggests several features for deprecation/modularization of the standard, in line with the XLIFF Technical Committee's deliberations, and successfully identifies the core features of XLIFF.     

Efficient autonomous signature exchange on ubiquitous networks

Fair signature exchange in emerging ubiquitous commerce (u-commerce) poses new security challenges. In particular, its operations are highly distributed and autonomous, and typically run on much open, dynamic and resource-diversified ubiquitous networks. These characteristics make the exchange very vulnerable to security attacks. Some effort has been made to address the challenges. As a result, an approach to autonomous fair exchange has been proposed specifically for u-commerce. Despite a number of novel features offered by the approach, its weaknesses are low efficiency and high complexity.This paper is aimed at proposing a more efficient and simpler solution for allowing the task of signature exchange to be delegated securely to selected devices in order to facilitate autonomous fair signature exchange on ubiquitous networks. To accomplish this aim, we have produced a novel approach to symmetric-key based verifiable proxy encryption to simplify the signature exchange delegation. Based on this approach, we have developed a new protocol for autonomous fair signature exchange in u-commerce. An analysis of the new protocol has been carried out to confirm its security, fairness and performance. A comparison with related work has demonstrated its better efficiency and simplicity.     

基于Web服务的网格体系结构及其支撑环境研究

网格技术是当前网络计算的前沿领域,基于Web服务技术构建网格系统有助于提高网格系统的可扩展性和互操作能力,是这一领域中的最新热点.但现有的工作尚未明确界定基于Web服务的网格的功能模型和实现机制.首先讨论了网格功能模型,基于OGSA(open grid service architecture)框架提出了基于Web服务的网格层次体系结构,并将Web服务工作流引入到网格任务描述中,给出一种Web服务与网格技术相融合的机制,介绍了基于Web服务的网格支撑环境WebSASE4G的总体结构和设计原理,为基于Web     

A data-driven VLSI array for arbitrary algorithms

The design of specialized processing array architectures, capable of executing any given arbitrary algorithm, is proposed. An approach is adopted in which the algorithm is first represented in the form of a dataflow graph and then mapped onto the specialized processor array. The processors in this array execute the operations included in the corresponding nodes (or subsets of nodes) of the dataflow graph, while regular interconnections of these elements serve as edges of the graph. To speed up the execution, the proposed array allows the generation of computation fronts and their cancellation at a later time, depending on the arriving data operands; thus it is called a data-driven array. The structure of the basic cell and its programming are examined. Some design details are presented for two selected blocks, the instruction memory and the flag array. A scheme for mapping a dataflow graph (program) onto a hexagonally connected array is described and analyzed. Two distinct performance measures-mapping efficiency and array utilization-and some performance results are discussed     

An approach for temporal analysis of email data based on segmentation

Many kinds of information are hidden in email data, such as the information being exchanged, the time of exchange, and the user IDs participating in the exchange. Analyzing the email data can reveal valuable information about the social networks of a single user or multiple users, the topics being discussed, and so on. In this paper, we describe a novel approach for temporally analyzing the communication patterns embedded in email data based on time series segmentation. The approach computes egocentric communication patterns of a single user, as well as sociocentric communication patterns involving multiple users. Time series segmentation is used to uncover patterns that may span multiple time points and to study how these patterns change over time. To find egocentric patterns, the email communication of a user is represented as an item-set time series. An optimal segmentation of the item-set time series is constructed, from which patterns are extracted. To find sociocentric patterns, the email data is represented as an item-setgroup time series. Patterns involving multiple users are then extracted from an optimal segmentation of the item-setgroup time series. The proposed approach is applied to the Enron email data set, which produced very promising results.     

A logical design tool for relational databases

A method is presented to prevent anomalies from affecting the design of a relational database. The approach, called the logical design tool (LDT), can also be used as an educational tool for the relational database. It allows certain problems that arise when the data is manipulated to be detected during design. An overview of LDT is followed by a discussion of its functions and its application     

Optimal matching of deformed patterns with positional influence

Deformations on patterns, such as substitutions, deletions, and insertions, are extended to be positionally dependent. The deformation of a primitive depends not only on its type, but also on its position. Concepts of contextual preserved deformations (CPD) and contextual variant deformations (CVD) are proposed, as are algorithms for optimal pattern matching under CPD and CVD conditions.     

求k邻域的体素栅格算法研究

给定一个度量空间中的一组数据点集,k邻域问题在于对于某个数据点求出按照该空间的距离度量离数据点最近的k个数据样本。目前主要有2种方法,一种是基于立方体分割形成的三维立方体体素索引数组的体素栅格（CG（Cell Grid）方法,另一种方法是基于树索引结构的方法如kd-Tree等。论文主要研究经典CG方法及解决其内存消耗过多问题的两个改进方法：排序体素栅格（SCG）方法和投影体素栅格（PCG）方法。CG、SCG、PCG算法采用了改进的搜索方法,避免了传统CG算法[2-4]可能得到错误k邻域的问题。对三种算法的时空性能进行了分析比较,给出了相应的实验比较数据。     

Reconstructive memory in case-based design

This paper describes an approach to applications of case-based reasoning in design based on utilising design methods used for solving similar problems in the past. In order to facilitate the implementation of this approach, data structures called MREM (Memory REconstruction Methods) are developed. This is based on Kolodner's theory of reconstructive memory. An MREM based model of design is implemented in a prototype called CADREM (CAse based Design using REconstruction Methods). CADREM's casebase contains cases of conceptual structural design of buildings.     

An Approach and Mechanism for Auditable and Testable Advanced Transaction Processing Systems

An architectural approach and a software mechanism is presented to enhance the auditability and testability of advanced transaction processing EDP systems. A high degree of auditability can be achieved through integrated support of auditability mechanisms as opposed to the traditional after-the-fact, ad hoc, add-on audit and test approaches. A programmable audit evidence gathering mechanism called an audit probe is proposed. A generic model of the audit probe is presented and its major features outlined. Audit hooks are proposed as standard probe interfaces for audit software. An overview of a high level audit-oriented audit probe definition language (APDL) for specifying the evidence gathering requirements for audit is highlighted. Audit test concurrent with the normal operation of the system and the capability of filtering only selected audit data are advocated. An example is presented illustrating the use of APDL and its value to auditing and quality control.     

广域异构环境下基于Agent的分布实时数据交换

广域异构环境下分布式实时数据交换越来越得到广泛的应用,由于操作系统,硬件设备,编程语言等的差异,使得广域异构环境的实时数据交换在系统的容错性,负载均衡,安全性等方面越来越受到挑战。为此,论文充分利用Agent在处理问题方面的自治性,反应性,以及移动性,提出了基于Agent的分布实时数据交换模型,对分布实时数据交换中的数据通信,任务调度,事务控制,数据存取等机制进行了详细的探讨。基于Agent的实时数据交换以一种透明的处理机制提供不同层次的信息交换,使得用户可以便利地利用Agent提供的编程接口实现大粒度对象复用,这对广域异构环境下的异构数据格式转换,包装器的构建,底层数据存取都带来了便利。同时基于Agent的数据交换具有良好的可扩展性和容错性以及安全性,为广域异构数据交换提供了一种可行的思路,对构建基于组件的多层分布式系统设计具有一定的参考价值。     

Psychovisual Evaluation of Lossy CMYK Image Compression for Printing Applications

In the digital prepress workflow, images are represented in the CMYK colour space. Lossy image compression alleviates the need for high storage and bandwidth capacities, resulting from the high spatial and tonal resolution. After the image has been printed on paper, the introduced visual quality loss should not be noticeable to a human observer. Since visual image quality depends on the compression algorithm both quantitatively and qualitatively, and since no visual image quality models incorporating the end-to-end image reproduction process are satisfactory, an experimental comparison is the only viable way to quantify subjective image quality. This paper presents the results from an intensive psychovisual study based on a two-alternative forced-choice approach involving 164 people, with expert and non-expert observers distinguished. The primary goal is to evaluate two previously published adaptations of JPEG to CMYK images, and to determine a visually lossless compression ratio threshold for typical printing applications. The improvements are based on tonal decorrelation and overlapping block transforms. Results on three typical prepress test images indicate that the proposed adaptations are useful and that for the investigated printing configuration, compression ratios up to 20 can be used safely.     

A distributed problem-solving approach to collaborative facility engineering

A framework for collaborative facility engineering is presented. The framework is based on a distributed problem-solving approach to collaborative facility engineering and employs an integration approach called Agent-Based Software Engineering as an implementation vehicle of this approach. The focal entity of this framework is a Multiagent Design Team (MDT) that comprises a collection of software agents (e.g. design software applications with a certain standard communication interface) and a design specialist, which together perform specific design tasks. Multiagent design teams are autonomous and form an organizational structure based on a federation architecture. Every multiagent design team surrenders its autonomy to a system program called facilitator, which coordinates the interaction among software agents in the federation architecture. Facilitators can be viewed as representatives of one or more teams that facilitate the exchange of design information and knowledge in support of the design tasks they perform. In the federation architecture, design specialists collaborate by exchanging design information with others via their software agents, and by identifying and resolving design conflicts by negotiation. In addition to a discussion of the framework's primary components, its realization in an integrated distributed environment for collaborative building engineering is described.