多维角色和任务的工作流访问控制模型

工作流系统中的安全访问控制技术已被予以很大的关注.本文在基于任务和角色的访问控制模型上提出了基于多维角色和任务的MR&TBAC模型.通过基于角色的静态授权和基于任务的动态授权加强了工作流系统访问控制的安全性.该模型解决了传统的访问控制模型的缺陷,提出了一种新的角色模型方便管理一定数量的角色,提高了分布式工作流系统的安全性和实用性.     

面向调控云的模型数据治理系统设计和实现

目前自动化运维人员直接在调控云上维护模型数据是一件任务巨大且重复性的工作.论文设计并实现面向调控云的模型数据治理系统,该系统通过数据抽取,数据治理,数据匹配和数据同步实现将现有调度系统的存量和增量模型数据的结构化,规范化,标准化同步至调控云模型数据云平台,并建立现有调度系统与调控云之间模型的映射关系.实际应用表明该系统能够较好地满足自动化运维人员的日常模型上云工作需求.     

基于LDAP和EJB的RBAC模型的实现

介绍了基于角色的访问控制(RBAC)模型及其在OA系统及其它企业应用系统中的应用.在此基础上提出了基于LDAP和EJB的RBAC模型的实现方案,并以实例验证了该应用模型的可行性.     

基于免疫识别原理和RFNN的复杂系统辨识

本文借鉴免疫识别原理,结合递归模糊神经网络(RFNN),提出了一种新的基于免疫化递归模糊神经网络的复杂系统辨识方法.其基本思想是,将复杂系统模型分解为可变部分与不变部分,不变模型描述系统平均动态行为,可变模型描述不确定性造成的系统实际行为对平均行为的偏差.以RFNN的隶属度函数神经元为构件,用它的各种组合构造不同的RFNN模型覆盖系统的可变模型空间,应用时采用免疫遗传算法在线筛选合适构件构造可变模型,识别系统扰动.仿真结果表明该方法能有效完成复杂不确定系统的快速在线识别.     

基于STEP和OSG的虚拟装配系统

针对传统虚拟装配系统中装配灵活性不足以及模型格式的局限造成的问题,对工业CAD设计中STEP标准进行了研究,并结合开源虚拟现实引擎OSG (OpenSceneGraph)的技术特点,设计出一个虚拟装配系统,并解决了其中关键技术问题,仿真出一个原型系统.系统采用OSG组织STEP产品模型的拓扑结构,并采用NURBS曲线曲面方法表达STEP模型的几何形状信息,将STEP模型读入系统,根据模型特征面、线之间的配合关系实现装配.系统的实现不仅增强了装配的灵活性,还使工业CAD与虚拟现实系统无缝结合、数据双向通信,同时也扩展了OSG的应用范围,从单纯的图形渲染走向虚拟装配制造领域.为虚拟装配设计、教学培训提供了方便有效地支持.     

一类时变系统中补偿器的功能和设计

PID控制器由于其结构简单和参数整定容易,具有良好的控制功能,被广泛应用在工程上的线性确定性系统中.但是,在非线性系统和不确定性系统中, PID控制器由于其固定的控制参数和结构限制,很难克服系统中内外干扰的影响,控制器鲁棒性能较差.本文按照被控对象中的标称模型设计常规PID控制器优化参数,对非线性系统中多个线性化模型和不确定性系统中的不同工作点模型,设计了一类补偿器,使得整个闭环系统具有与标称模型下相同的控制品质.工程应用例子论证了本文提出的补偿器能提高不确定与非线性系统的控制品质和鲁棒性能.     

实时CORBA系统调度模型的分析和比较

实时CORBA系统需要解决如何将有限的计算资源和通信资源分配给实时任务,从而保证端到端执行时间的可预测性需求的问题.为了更好地定量分析可预测性,需要为以固定优先级方式调度的、周期性任务的硬实时CORBA系统建模.文中分析了TAO系统和NraD/URI系统的调度模型以及分别由Bettati ＆ Sun提出和由东南大学提出的端到端调度模型的模型描述和调度方式.在调度模型的描述能力、计算能力、适用范围和存在的联系等方面对上述调度模型进行了分析和比较.     

系统直和博弈模型下的合作演化

演化博弈论是生物进化论与博弈论结合产生的理论,已成为研究合作演化行为的有力工具.本文研究了基于系统直和博弈模型下的合作演化行为.首先,利用复制者方程分析了双人双策略及三策略对称博弈的演化动力学过程.然后,以石头剪刀布模型和雪堆模型为基础,采用矩阵直和构建系统直和博弈模型,并将所构造的直和矩阵转化为含参数的系统总支付矩阵.随后,说明了这种方法可推广到n个博弈的情形.最后,利用MATLAB对系统直和博弈模型进行仿真模拟,从系统整体的角度分析合作演化.仿真结果表明,混合之后的系统直和博弈较单一博弈而言,合作策略的占比明显增加,且整个系统稳定性更好.这种合作演化机制呈现了全局互惠.     

基于GA和单纯形法的直流电机参数辨识

提出一种基于优化算法的非线性系统参数辨识的方法.针对直流电机非线性摩擦力和饱和特性,建立直流电机的非线性模型.利用遗传算法的全局寻优特性和单纯形法快速的收敛性,通过获取充分激励的实际系统运行的输入输出数据,辨识出包括非线性摩擦力在内的直流电机所有的8个模型参数.获取系统实际运行的输入输出数据,分别验证电机运行于死区、饱和区和线性区时,模型辨识的精度.这种方法可以方便地应用于其他非线性系统参数辨识中.     

基于UML的计费系统的建模和实现

本文详细介绍了基于UML描述的计费系统的建模过程,包括需求模型、对象结构模型、行为模型和实现模型,并就系统实现中的一些关键技术进行了探讨.     

UNIFAC及其改进模型的评价研究

用UNIFAC及其修正模型估算了含芳香烃、二甲苯同分异构体和极性物质体系的汽液平衡,并将计算结果与实验数据相比较。结果表明,原始UNIFAC模型对含二甲苯同分异构体体系计算精度高于UNIFAC(Larsen)模型和UNIFAC(Dortmund)模型好,而对于极性或弱极性体系,则后2种模型结果较令人满意,但对于强极性体系偏差较大。     

Verification of clocked and hybrid systems

This paper presents a new computational model for real-time systems, called the clocked transition system (CTS) model. The CTS model is a development of our previous timed transition model, where some of the changes are inspired by the model of timed automata. The new model leads to a simpler style of temporal specification and verification, requiring no extension of the temporal language. We present verification rules for proving safety a nd liveness properties of clocked transition systems. All rules are associated with verification diagrams. The verification of response properties requires adjustments of the proof rules developed for untimed systems, reflecting the fact that progress in the real time systems is ensured by the progress of time and not by fairness. The style of the verification rules is very close to the verification style of untimed systems which allows the (re)use of verification methods and tools, developed for u ntimed reactive systems, for proving all interesting properties of real-time systems. We conclude with the presentation of a branching-time based approach for verifying that an arbitrary given CTS isnon-zeno. Finally, we present an extension of the model and the invariance proof rule for hybrid systems. Received: 23 September 1998 / 7 June 1999     

Driver acceptance of car navigation systems: integration of locational accuracy,processing speed,and service and display quality with technology acceptance model

By utilizing and extending the technology acceptance model, this study introduces a new integrated model that analyzes driver acceptance of car navigation systems. The current study conducts in-depth interviews and explores psychological factors that may be significantly related to the usability of car navigation systems. Data collected from 1,181 drivers via an online survey are statistically analyzed using structural equation modeling. Results indicate that the proposed research model accurately predicts driver acceptance of car navigation systems. The model identifies perceived processing speed and locational accuracy of car navigation systems as key psychological constructs, and reveals that satisfaction plays a moderate role. Theoretical implications and practical implications for improving car navigation systems are discussed.     

Wave-Based Analysis and Control of Lump-Modeled Flexible Robots

Flexible robots are frequently represented by lumped models. In the mechanics of lumped systems, wave concepts have been avoided, for good reasons, generally. In the control of lumped flexible systems, however, wave concepts prove very fruitful. This paper provides a foundation for the wave-based control application by exploring the validity and nature of wave concepts in lumped robotic systems. A new wave-based model of uniform mass-spring systems is proposed and verified. The model is exact but not unique. Useful simplifications and approximations are also presented. The model leads to control strategies for flexible robotic systems that are simple, powerful, robust, and generic. The wave approach also provides a new analysis tool and conceptual framework for lumped dynamic systems     

模拟实时系统的点区间优先级时间Petri网与TCTL验证

时间Petri网为实时系统提供了一种形式化的建模方法, 时间计算树逻辑(TCTL)为描述实时系统与时间相关的设计需求提供了一种逻辑化的表达方式, 因此基于时间Petri网的TCTL模型检测广泛应用于实时系统的正确性验证.然而对于一些涉及优先级的实时系统, 例如多核多任务实时系统, 这里不仅需要考虑任务之间的时间约束还要考虑任务执行的优先级以及引入优先级带来的抢占式调度问题, 致使相应的建模和分析变得更加困难.为此, 本文提出了点区间优先级时间Petri网, 通过在时间Petri网上定义变迁发生的优先级以及变迁的可挂起性, 从而可以模拟实时系统的抢占式调度机制, 即首先高优先级的任务抢占低优先级的任务所占用的资源, 导致后者被中断, 然后前者执行完毕后释放资源, 最后后者再次获得资源从中断的地方恢复.本文通过点区间优先级时间Petri网来模拟多核多任务实时系统, 使用TCTL来描述它们的设计需求, 设计了相应的模型检测算法, 开发了相应的模型检测器以验证它们的正确性.我们通过一个实例来说明我们的模型和方法的有效性.     

基于模型参考和内模原理的线性系统鲁棒控制设计

不确定性因素会使系统性能恶化,它包括系统不确定性参数和各种外部干扰等.本文针对这种不确定性线性系统,利用模型参考和内模原理,建立鲁棒控制系统结构,分析了其能控性条件,通过选择参考模型和内模实现系统能控,在此条件下,将鲁棒控制设计转换为控制系统的LQR问题进行研究,并运用最优控制理论,计算其反馈控制律.仿真结果表明该设计方法将"模型参考"与"内模原理"有机结合起来,提高了系统的鲁棒稳定性,有效抑制干扰,并实现系统性能的改善.     

Sampled-data models for affine nonlinear systems using a fractional-order hold and their zero dynamics

One of the approaches to sampled-data controller design for nonlinear continuous-time systems consists of obtaining an appropriate model and then proceeding to design a controller for the model. Hence, it is important to derive a good approximate sampled-data model because the exact sampled-data model for nonlinear systems is often unavailable to the controller designers. Recently, Yuz and Goodwin proposed a more accurate model than the simple Euler model in the case of a zero-order hold. This article derives a sampled-data model for nonlinear systems using a fractional-order hold, and analyzes the zero dynamics of the sampled-data model.     

Neighborhood systems and approximate retrieval

An approximate retrieval model is proposed based on the notion of neighborhood systems. The knowledge used in the model consists of an information table, in which each object is represented by its values on a finite set of attributes, and neighborhood systems on attribute values, which provide semantic similarity or closeness of different values. An information table can be used for exact retrieval. With the introduction of neighborhood systems to information tables, one is able to perform approximate retrieval. Operations on neighborhood systems are introduced based on power algebras. An ordering relation representing the information of a neighborhood system is suggested and examined. Approximate retrieval is carried out by the relaxation of the original query using neighborhood systems, and the combination of intermediate results using neighborhood system operations. The final retrieval results are presented according to the proposed ordering relation. In contrast to many existing systems, a main advantage of the proposed model is that the retrieval results are a non-linear ordering of objects.     

A comparative analysis of the usage and infusion of wiki and non-wiki-based knowledge management systems

Antecedents of adoption and diffusion in time-honored models such as the technology acceptance model and innovation diffusion theory may not provide sufficient measures for newer Web 2.0 technologies such as wikis. This research examines two potential extensions to the basic tenets of user acceptance: reciprocity expectation and personal innovativeness in information technology (IT). The research also examines an advancing technology: wiki technology-based knowledge management systems. Based on the results of an online survey, partial least squares analysis is used to evaluate the proposed model and provide comparative results for traditional knowledge management systems and wikis. Of the 170 respondents, 46 indicated wiki-based systems as their primary knowledge management system, while 124 indicated non-wiki-based systems as the primary system. The results indicate the set of factors influencing usage are different than the factors influencing infusion. Further, non-wiki-based versus newer wiki-based knowledge management systems have different sets of factors affecting usage and infusion. Both extensions to the base model have a greater impact on wiki-based systems as opposed to non-wiki-based systems. Reciprocity expectation was found to have a contradictory significant negative influence on infusion of wikis. Additionally, personal innovativeness in IT moderates the usage and infusion of wikis more so than for traditional knowledge management systems. These results support a more robust model for analyzing the utilization of such technologies.     

一种嵌套中断系统的建模和分析方法

在嵌入式系统和各类操作系统中,中断机制是确保实时响应各类异步事件的重要方法.通常在处理一个中断事件的过程中,往往会有更紧迫的中断事件请求响应,因而发生中断嵌套.建模并验证嵌套中断系统是一个具有挑战性的工作.本文提出一种建模和验证嵌套中断系统的方法.首先,为中断系统提出了基于投影时序逻辑的定义,并将这种定义推广到包含任意多中断事件的中断系统上,从而得出嵌套中断系统基于投影时序逻辑的形式化模型.其次,使用投影时序逻辑定义的基本中断语句扩充建模仿真和验证语言（MSVL）并扩展MSVL语言的解释器使其可以对嵌套中断系统进行建模仿真和验证.最后通过一个实例展现本文所提出的方法的正确性和实用性.