电网设备监测系统访问控制模型研究

传统的基于角色的访问控制（RBAC）模型角色分配方式单一,权限模块功能过于简单,难以满足当今日趋复杂的系统需求。文中从角色分配方式和权限配置模块入手,增加了“角色组”的概念,提出了配置权限的三部分内容,形成了改进的 RBAC 模型;并且针对某电网公司的设备监测系统中权限分配的问题,设计出了适用于该系统的一套灵活的权限管理模式,有效的解决了该系统的用户权限的管理问题,且由于灵活性强,能很好地适应业务需求的发展和变化。     

RBAC模型在医疗系统中的研究与应用

基于角色的访问控制是目前应用在系统控制用户访问中比较主流的一门技术。在此针对医疗系统的特点,在基于角色的访问控制模型的基础上,分析医疗系统中的访问主体和客体,引入角色,将权限和角色相关联,重点研究不同用户对记录的访问控制,提出一个访问控制算法,通过分配用户适当的角色,然后授予用户适当的访问权限,使用户和访问权限逻辑分离,从而提高了在医疗系统中权限分配和访问控制的灵活性与安全性。     

面向对象的基于角色访问控制模型的探讨

提出一种应用于分布式系统的面向对象的基于角色访问控制(ORBAC)模型。基于角色访问控制,将权限与角色相关联,用户分配得多个角色从而获得与其关联的权限。引用对象的概念,通过策略控制器集中控制分散管理,为分布式系统提供高效的访问控制机制。模型考虑了静态和动态角色分配,并分析了面向对象访问控制模型的一些动态特性。     

一种RBAC优化模型在大型煤矿ERP系统中的应用

基于角色的访问控制(RBAC)主要研究将用户划分成与其在组织结构体系相一致的角色,是一种解决统一资源访问控制的有效方法.然而,大型煤矿ERP系统中涉及了大量的资源和用户,这些资源和用户还处于不断的变化中.传统的RBAC模型难以满足大型ERP在权限管理时复杂多变、灵活快捷的要求.在研发一个大型国有煤矿权限系统的过程中,提出了一种扩充的RBAC动态权限管理模型,引进用户组、权限组来强化角色的权限分配,大大增强了大型ERP对权限管理的便捷性和灵活性.     

扩展RBAC访问控制模型在家庭开放平台中的应用

基于角色的访问控制（role-based access control,RBAC）技术是目前访问控制领域研究的热点,具有灵活和高效的特点。在RBAC模型的基础上,将权限进行细化,添加了对象、操作、域和分组4个要素,提出了域的可继承性,深入地控制角色可管理的数据内容和操作,提供了更细粒度化的权限功能。将扩展后的模型作为解决家庭开放平台终端管理子系统分权分域问题的理论基础,解决了系统中访问控制约束的问题,提出了多样化的角色和权限设计方案,实现了复杂的职责分配。     

动态角色访问控制模型的研究与应用

文章在回顾当前的访问控制研究状况和进展的基础上,提出了一个动态角色分级访问控制模型。在该模型中,引入了角色扮演者概念和分级角色管理机制,有效增强了在教务管理系统中访问控制的灵活性、独立性和扩展性,完善了教务管理系统的权限管理,提高了安全性,为教务管理系统提供了更为全面的访问控制机制。     

一种基于扩展角色的访问控制模型和方法

针对传统的基于角色访问控制（RBAC）模型的不足,在基于角色的权限访问控制的基础上,提出了一个扩展角色访问控制模型,新模型对角色和权限的概念进行了扩展,使得RBAC模型能够更灵活、高效地对系统进行权限访问控制,增强了访问控制安全。     

基于角色与信任的访问控制及其在Hadoop上的实现

Hadoop云计算平台已经成为当今社会最流行的平台之一,它的安全问题也在改进,访问控制是保护Hadoop平台安全的一种有效途径。依据基于角色的访问控制和基于信任的访问控制,并在此基础上进行改进,提出一种基于角色与信任的访问控制模型。该模型主要根据Hadoop平台的日志文件,运用神经网络算法对日志文件进行分析,以此来获得每一个用户的信任度。集群根据用户的信任度来分配用户拥有的权限。     

基于型号装备-角色的IETM访问控制研究

针对交互式电子技术手册应用中的管理和安全保密需求,在分析传统访问控制模型的基础上,提出基于型号装备-角色的访问控制模型。该模型包括用户、型号装备、装备用户、角色、权限、操作访问控制规则、数据访问控制规则等,支持功能操作权限和数据权限分离,支持以型号装备结构为基础的细粒度数据访问控制以及以角色、装备用户为基础的功能操作访问控制定义和管理,给出了权限定义和权限计算方法。根据IETM的功能及数据访问控制需求,对交互式电子技术手册访问控制进行软件功能、控制流程及数据模型设计。采用J2EE及Web Service技术开发模块组件,实现交互式电子技术手册层级式、细粒度访问控制。     

一种适合大型分布式应用的PMI系统设计

文章针对公钥基础设施的不足,提出了一种适合大型分布式应用系统的权限管理基础设施模型（MPMI）,采用基于角色的访问控制思想来实现权限的分配,通过角色分配证书和角色规范证书来实现权限的管理,并对系统应用于校园网的情况进行分析,取得了较好效果。     

基于规则的自动化授权方法研究

论文深入剖析了RB—RBAC此完成权限自动分配的授权管理方法。难以解决的授权管理问题。模型并结合用户的身份管理,提出了一种根据用户属性它能满足分布环境、用户数量巨大、权限分配关系复杂、制定授权规则,并据使用传统的管理方法     

一种新的空时无线信道模型及其计算机模拟方法

信道模型对分析智能天线系统的性能是非常重要的。针对基于(散射体)几何分布的单反射椭圆模型(GBsBEM)在计算机模拟时参数难以确定的不足,本文结合UMTS-IMT-2000推荐的信道模型,提出了一种新的空时信道模型,并给出了计算机模拟方法:以GBSBEM模型为基础,吸收UMTS-IMT-2000推荐的信道模型的时延和功率方面的参数并考虑GBSBEM模型中DOppler效应对信号幅度的影响,模拟空时Rayleigh信道。在这一方法的基础上,又提出了多用户空时信道简化模型以及模拟方法。计算机仿真结果表明,所提出的信道模型计算机模拟方法是可行的。     

Medical X-Ray Image Enhancement Based on Kramer''''s PDE Model

The purpose of this study is to present an application of a novel enhancement technique for enhancing medical images generated from X-rays. The method presented in this study is based on a nonlinear partial differential equation (PDE) model, Kramer’s PDE model. The usefulness of this method is investigated by experimental results. We apply this method to a medical X-ray image. For comparison, the X-ray image is also processed using classic Perona-Malik PDE model and Catte PDE model. Although the Perona-Malik model and Catte PDE model could also enhance the image, the quality of the enhanced images is considerably inferior compared with the enhanced image using Kramer’s PDE model. The study suggests that the Kramer’s PDE model is capable of enhancing medical X-ray images, which will make the X-ray images more reliable.     

On the characteristic of the deep-depletion SOS transistor

An improved characterization of the conduction properties of deep-depletion SOS transistor is presented. The new model provides a continuous characterization of film conduction from strong accumulation to strong depletion. A comparison is made between the simple quadratic model and the new model. It is shown that the finite electrostatic surface potential of a strongly accumulated layer can be represented as a slight threshold shift in the quadratic model. Conduction characteristics for weak accumulation, which has never been studied before, is also compared with the characteristics of the quadratic model. The new model is also used to generate characteristic curves that closely match empirical characteristic curves.     

Medical X-Ray Image Enhancement Based on Kramer's PDE Model

The purpose of this study is to present an application of a novel enhancement technique for enhancing medical images generated from X-rays. The method presented in this study is based on a nonlinear partial differential equation (PDE) model, Kramer's PDE model. The usefulness of this method is investigated by experimental results. We apply this method to a medical X-ray image. For comparison, the X-ray image is also processed using classic Perona-Malik PDE model and Catte PDE model. Although the Perona-Malik model and Catte PDE model could also enhance the image, the quality of the enhanced images is considerably inferior compared with the enhanced image using Kramer's PDE model. The study suggests that the Kramer's PDE model is capable of enhancing medical X-ray images, which will make the X-ray images more reliable.     

关于传输线等效集总电路模型的拓展教学

传输线的等效集总电路模型有助于理解和掌握传输线的基本概念,并可用于电特性的仿真分析。本文分别探讨了在教学过程中需拓展的两个重要知识点。其一,在高频工作情况下,需要对含有频变分布参数的传输线进行准确建模,获取相应的等效集总电路模型;其二,在分析多导体构成的耦合传输线时,等效集总电路模型同样值得探究。     

High resolution parametric modelling for two-dimensional radar target using prony algorithm

On the conditions of low-resolution radar, a parametric model for two-dimensional radar target is described here according to the theory of electromagnetic scattering and the geometrical theory of diffraction. A high resolution estimation algorithm to extract the model parameters is also developed by building the relation of the scattering model and Prony model. The analysis of Cramer-Rao bound and simulation show that the method here has better statistical performance. The simulated analysis also indicates that the accurate extraction of the diffraction coefficient of scattering center is restricted by signal to noise ratio, radar center frequency and radar bandwidth.     

Task-oriented design method and research on force compliant experiment of six-axis wrist force sensor

This paper analyzes the task-oriented design method of six-axis force sensor and proposes the task model of the sensor. The task mathematical model of the sensor is established based on the idea of task ellipsoid. The models of force ellipsoid and moment ellipsoid are also established. The relational expression between the task model and ellipsoid model of sensor is obtained. Then, a fully pre-stressed dual-layer parallel six-axis wrist force sensor is proposed, whose static mathematical model is also established. The sensor task model for assembly work is proposed and the analytical expression between the sensor structure parameters and task model is deduced. According to the assembly work, the sensor structure is designed specifically, and the specific structure sizes of the sensor are obtained. Then the new sensor prototype manufactured for peg-in-hole assembly is processed. The calibration experiment and peg-in-hole assembly experiment on the prototype are completed and each performance index is well examined by the experiment results. The experiment results also lay the foundation for the practical application of six-axis force sensor.     

分数傅里叶域上宽间隔跳变的透明语音信息隐藏模型

语音信息隐藏一直是信息安全领域内研究的热点和难点。本文基于掩蔽效应和扩频码理论,提出了一种新的基于跳变分数傅里叶变换的高透明语音信息隐藏模型,首先从时频域掩蔽出发,提出了分数傅里叶变换域上的隐秘信息嵌入算法,并提出了在分数相关倒谱域上的隐秘信息提取算法。同时又提出了一种宽间隔多进制伪随机序列来控制分数阶因子α。理论分析和实验结果表明,该模型具有很强的透明性,在时域、频域和倒谱域都无法发现隐秘信息的存在,同时能够抗信道噪声的影响。研究表明该模型在语音信息隐藏领域具有较高的应用价值和广阔的应用前景。      

Fitted Elmore delay: a simple and accurate interconnect delay model

In this brief, we present a new interconnect delay model called fitted Elmore delay (FED). FED is generated by approximating HSPICE delay data using a curve fitting technique. The functional form used in curve fitting is derived based on the Elmore delay (ED) model. Thus, our model has all the advantages of the ED model. It has a closed-form expression as simple as the ED model and is extremely efficient to compute. Interconnect optimization with respect to design parameters can also be done as easily as in the ED model. In fact, most previous algorithms and programs based on ED model can use our model without much change. Most importantly, FED is significantly more accurate than the ED model. The maximum error in delay estimation is at most 2% for our model, compared to 8.5% for the scaled ED model. The average error is less than 0.8%. We also show that FED can be more than 10 times more accurate than the ED model when applied to wire sizing.