基于瘦客户机终端的同步协同方法中界面更新的研究

本文介绍了瘦客户机的体系特点,同步协同技术的特点.并在瘦客户机模式基础上提出了基于同步协同设计方法的终端界面更新策略、客户端图形界面的显示的研究方法,初步解决了同步协同设计领域存在的环境异构性、协同实时性等难点问题.并对实时协同设计过程中,同步性问题的产生原因进行分析,同时提出了较为完善的解决方案.该文还通过与PC机比较分析了瘦客户机的应用优势.     

协同图形编辑系统中并发操作冲突检测的研究

实时协同设计是CSCW应用的重要领域。实时协同设计过程实际上就是并发冲突产生和消解的过程。本文描述协同图形编辑系统中多对象之间的冲突相关定义,提出一种判别并发操作冲突的关联对象冲突检测策略,设计实现相应的冲突检测算法,最后对算法的可行性进行分析。     

多版本技术中相同操作的处理策略

意愿保证是协同编辑系统中的关键问题之一,其研究具有挑战性.多版本技术通过对象复制策略有效地解决实时协同图形编辑系统中的冲突操作的意愿保证问题.本文分析了编辑中一类重要操作--相同操作在多版本技术及其对象标识中存在的问题,提出了一个对象版本标识解决方案和相关的策略,并讨论了相同操作对操作历史日志的维护的影响和改进.实验表明,本文提出的方法有效地完善了多版本技术中对不同操作的处理.     

实时协同设计系统中同步过程的研究

作为一类支持人机交互的分布式系统,实时协同设计系统允许多个用户通过网络同步的对同一文档进行编辑.实时性、分布式、用户操作无限制是该系统的3个重要要求,但由于用户的同步操作和网络传输延迟的存在,协同过程中容易产生各种不同步的现象.对由于站点迟到或者非正常退出协同设计系统而引起的同步性问题进行了研究,提出了同步过程,包括主控站点发送同步队列、状态矢量轮询、缺少操作补齐等步骤,解决了站点迟到或非正常退出系统而引起的同步性问题.     

面向图形对象的协同设计系统的设计与实现

协同图形编辑是协同设计的一个重要研究方向,支持自然和谐的多用户并发交互是协同图形编辑的重点内容之一。对协同图形编辑系统的进行了设计,提出了相应的解决方案和技术措施。最后在Socket的基础上,给出一个协同图形编辑系统实例的初步探索。     

图形编辑过程冲突消解策略研究

冲突是协同图形编辑系统中的常见现象,合理地解决冲突是图形协同编辑的关键问题。讨论了协同图形编辑系统冲突消解问题,主要研究内容包括基于时间和空间干涉的冲突检测策略、交互事务分组策略,以及基于事务相关树的冲突消解策略。最后以手势为交互手段开发了一个采用冲突消解策略的协同图形编辑原型系统,目前该系统已经试用。     

基于图形对象的一致性维护问题的研究

针对实时协同图形编辑系统中一致性维护关键问题,提出了一种基于图形对象的并发控制算法。该算法扩展了面向文本编辑的分布式操作转换dOPT算法,满足图形对象属性级上数据一致性维护,同时通过预定义图形对象间的关联关系和位置属性约束规则,进行操作语义维护管理,使得实时协同图形编辑系统的一致性维护更为有效和完备。     

多版本技术中的对象标识及其压缩

协同编辑系统支持不同地域的协作者通过网络同时地编辑同一个文本或图形对象,其研究具有挑战性.介绍了协同图形编辑中的多版本技术,重点讨论了对象标识及其策略,给出所存在的问题.提出了一个全面的对象标识方案.该方案解决了以往方案不能处理具有依赖关系的操作和相同关系的操作的对象标识和系统维护问题.同时,随着编辑的进行和冲突的产生,对象标识会急剧膨胀,影响系统处理的效率,分析了对象标识压缩的规则,给出一个对象标识压缩方法,并对其有效性进行了分析.实例分析和实验结果表明,所提出的对象标识及其压缩方案提高了系统的效率.     

协同图形编辑系统设计与实现

给出了基于图形对象的协同编辑系统的操作冲突／相容关系及其基于逻辑时间钟的检测方法和一致性保证算法。在此基础上，讨论了一个实时协同图形编辑系统的设计方面有关的关键技术。实验结果表明，该方法是可行和有效的。     

协同多版本技术中的中间版本

首先对协同图形编辑的研究现状和存在问题进行了讨论,然后针对并发操作的冲突和分类,在基于版本复制的分布协同多版本技术的基础上,提出了中间版本的存在必要性及其表示和效果显示方法.     

Protection of Database Security via Collaborative Inference Detection

Malicious users can exploit the correlation among data to infer sensitive information from a series of seemingly innocuous data accesses. Thus, we develop an inference violation detection system to protect sensitive data content. Based on data dependency, database schema and semantic knowledge, we constructed a semantic inference model (SIM) that represents the possible inference channels from any attribute to the pre-assigned sensitive attributes. The SIM is then instantiated to a semantic inference graph (SIG) for query-time inference violation detection. For a single user case, when a user poses a query, the detection system will examine his/her past query log and calculate the probability of inferring sensitive information. The query request will be denied if the inference probability exceeds the prespecified threshold. For multi-user cases, the users may share their query answers to increase the inference probability. Therefore, we develop a model to evaluate collaborative inference based on the query sequences of collaborators and their task-sensitive collaboration levels. Experimental studies reveal that information authoritativeness, communication fidelity and honesty in collaboration are three key factors that affect the level of achievable collaboration. An example is given to illustrate the use of the proposed technique to prevent multiple collaborative users from deriving sensitive information via inference.     

产品图纸异地同步与实时协作设计系统研究

从制造业企业联盟生产实际出发，分析了异地设计、异地制造产品图纸同步与实时协作设计的客观需求，研究了产品图纸异地同步与实时协作设计系统应具有的功能，提出了以虚拟专用网(VPN)为物理平台、基于Web的图纸数据同步更新和基于网络黑板的实时协作设计解决方案，讨论了实现该方案的组成结构及关键技术，总结了该方案的特点。     

Modified collaborative optimization for feasibility problem of final solution

This paper focuses on the feasibility problem of the final solution obtained by the relaxation collaborative optimization method. First, a mixed relaxation (MR) method is developed to enhance the possible premature convergence and non-solution problems of the variable relaxation method. Then the feasibility problem of the final solution is analyzed, that is the optimal solution obtained from system level may not satisfy the constraints of original optimization problem due to the inconsistency between system level and subsystem level for shared variables. A method of modified collaborative optimization (MCO) is put forward to solve this problem. In this method, the impact of the inconsistency is considered and supplemented in the subsystem-level constraints in order to approximate the original constraints as much as possible. At last, based on the MR method, the feasibility problem of the final solution is illustrated by three examples, and the effectiveness and accuracy of MCO are demonstrated by the optimization results.     

面向多ISP协同的域间路由策略管理方法

域间路由系统由多个自治系统互连而成,各自治系统根据自身的商业目标独立配置路由策略。由于各网络服务提供商（ISP）的策略隐私性以及边界网关协议（BGP）设计和实现上的缺陷,目前的域间路由系统在协同配置和协同安全方面存在明显的不足,对路由策略冲突,路由信息欺骗等问题缺乏有效的解决手段。域间路由协同策略管理方法采用分布式协同结构,利用隐私隐藏信息共享的方法,能够在实现自治系统隐私保护的前提下发现自治系统之间可能存在的路由策略冲突,解决各ISP在独立情况下无法进行的策略优化。     

An Internet-based intelligent design system for injection moulds

The rapid growth of Internet and information technologies in recent years provides a solution to support and facilitate collaborative product developments among different geographically distributed enterprises. An effective and feasible tool to aid the collaborative development of injection moulds can be realized by developing an Internet-based mould design system as one of the modules of a collaborative product development system. This paper presents a prototype Internet-based intelligent design system for injection moulds. The architecture of the system consists of an interactive KB mould design system embedded in an Internet environment. A Java-enabled solution together with artificial intelligence techniques is employed to develop such a networked interactive CAD system. In this system, the computational module, the knowledge base module and the graphic module for generating mould features are integrated within an interactive CAD-based framework. The knowledge base of the system would be accessed by mould designers through interactive programs so that their own intelligence and experience could also be incorporated with the total mould design. The approach adopted both speeds up the design process and facilitates design standardization which in turn increases the speed of mould manufacture. A practical case study is presented to illustrate the operations of the Internet-based mould design system.     

实时图案协同设计中冲突问题的研究

在Internet环境中,允许多个用户同时对同一图案的任意绘图区进行设计是图案协同设计系统应满足的基本要求．然而不同设计者在协同设计过程中由于设计意图的不同而引起的操作冲突是不可避免的,因此冲突问题是图案协同设计系统的关键问题之一．着重讨论了冲突的定义,冲突的多种避免方式,提出了高效的冲突检测算法和一种能保护用户协同设计意图的冲突解决方法——基于冲突操作锁定的冲突解决方法．这些方法和算法的实现使得在分布式计算环境下协同设计的冲突问题得到了较完善的解决．     

A method for topological entity correspondence in a replicated collaborative CAD system

In order to utilize the potential advantages of replicated collaborative CAD system to support natural, free, fast and less-constrained multi-user human-to-human interaction, a local-locking mechanism, which can provide fast modeling response, is adopted as concurrency control mechanism for a replicated on-line collaborative CAD system. A human–human interactive modeling is achieved by immediate local execution of modeling operations and exchange of modeling operations across all collaborative sites real-time. In particular, an approach to achieve topological entity correspondence across collaborative sites during modeling procedure, which is critical to guarantee the correctness and consistency of collaborative modeling result, is proposed. A prototype system based on the ACIS geometric modeling kernel is implemented to verify availability of the proposed solution.     

Detecting inappropriate access to electronic health records using collaborative filtering

Many healthcare facilities enforce security on their electronic health records (EHRs) through a corrective mechanism: some staff nominally have almost unrestricted access to the records, but there is a strict ex post facto audit process for inappropriate accesses, i.e., accesses that violate the facility’s security and privacy policies. This process is inefficient, as each suspicious access has to be reviewed by a security expert, and is purely retrospective, as it occurs after damage may have been incurred. This motivates automated approaches based on machine learning using historical data. Previous attempts at such a system have successfully applied supervised learning models to this end, such as SVMs and logistic regression. While providing benefits over manual auditing, these approaches ignore the identity of the users and patients involved in a record access. Therefore, they cannot exploit the fact that a patient whose record was previously involved in a violation has an increased risk of being involved in a future violation. Motivated by this, in this paper, we propose a collaborative filtering inspired approach to predicting inappropriate accesses. Our solution integrates both explicit and latent features for staff and patients, the latter acting as a personalized “fingerprint” based on historical access patterns. The proposed method, when applied to real EHR access data from two tertiary hospitals and a file-access dataset from Amazon, shows not only significantly improved performance compared to existing methods, but also provides insights as to what indicates an inappropriate access.     

基于网络和通用字处理软件的文档协同编著系统

在实际过程中，多人协同编著同一份文档的情况普遍存在。以建设领域为例，各种项目建议书、可行性研究报告等都需要多人协同完成。但是，目前常用的文档编辑软件均未对多人协同编著提供支持。 为此，该文在分析相关研究的基础上，提出了一个基于网络和通用字处理软件开发文档协同编著系统模型，并开发了原型系统，为文档协同编著系统的开发提供了一条新途径。