在嵌入式软件开发早期,为其建立可靠性模型能够尽早发现软件设计中存在的问题,从而节约嵌入式软件开发成本。AADL从软件结构和故障传播两个角度来建立软件可靠性模型,但是AADL的半形式化性质使得基于AADL建立的可靠性模型难以对可靠性...在嵌入式软件开发早期,为其建立可靠性模型能够尽早发现软件设计中存在的问题,从而节约嵌入式软件开发成本。AADL从软件结构和故障传播两个角度来建立软件可靠性模型,但是AADL的半形式化性质使得基于AADL建立的可靠性模型难以对可靠性、安全性等非功能属性进行严格的分析与验证。形式规格说明语言Z语言具有很强的逻辑描述能力,能够精确表达软件中的各种约束,这使得基于Z语言建立的可靠性模型能够很好地进行严格的分析和验证。因此,考虑到AADL和Z的特征,文中提出了一种将AADL与Z相结合的形式化可靠性模型(embedded software Reliability Model combined with Z and AADL,ZARM),该模型具有AADL的描述能力和Z的精确性。文中给出了ZARM故障模型、结构模型和行为模型的建模方法,并在谓词中描述了与可靠性相关的数据约束。在ZARM模型的基础上,文中提出了一种面向概率的基于DTMC的可靠性评估方法,来对ZARM模型进行可靠性定量评估和分析。最后,通过一个飞行管理系统对应用ZARM模型进行可靠性建模的过程进行了说明,并采用所提评估方法对其进行了可靠性评估。评估结果与文献[19]结果的对比说明了所提方法的正确性和有效性。展开更多
In recent times, computer based systems are frequently used for protection and control in the various industries viz Nuclear, Electrical, Mechanical, Civil, Electronics, Medical, etc. From the operating experience of ...In recent times, computer based systems are frequently used for protection and control in the various industries viz Nuclear, Electrical, Mechanical, Civil, Electronics, Medical, etc. From the operating experience of those computer based systems, it has been found that the failure of which can lead to the severe damage to equipments or environmental harm. The culprit of this accident is nobody other than our software, whose reliability has not been ensured in those conditions. Also for real time system, throughput of the system and average response time are very important constructs/ metrics of reliability. Moreover neither of the software reliability model is available which can be fitted generically for all kinds of software. So, we can ensure reliability at the early stage i.e. during design phase by architecturing the software in a better way. The objective of this paper is to provide an overview of the state-of-the-art research in the area of architecture-based software reliability analysis. We then describe the shortcomings and the limiting assumptions underlying the prevalent research. We also propose various approaches which have the potential to address the existing展开更多
In anomaly detection, a challenge is how to model a user＇s dynamic behavior. Many previous works represent the user behavior based on fixed-length models. To overcome their shortcoming, we propose a novel method base...In anomaly detection, a challenge is how to model a user＇s dynamic behavior. Many previous works represent the user behavior based on fixed-length models. To overcome their shortcoming, we propose a novel method based on discrete-time Markov chains （DTMC） with states of variable-length sequences. The method firstly generates multiple shell command streams of different lengths and combines them into the library of general sequences. Then the states are defined according to variable-length behavioral patterns of a valid user, which improves the precision and adaptability of user profiling. Subsequently the transition probability matrix is created. In order to reduce computational complexity, the classification values are determined only by the transition probabilities, then smoothed with sliding windows, and finally used to discriminate between normal and abnormal behavior. Two empirical evaluations on datasets from Purdue University and AT＆T Shannon Lab show that the proposed method can achieve higher detection accuracy and require less memory than the other traditional methods.展开更多
One of the challenging tasks in cognitive radio(CR) networks is to agree on a common control channel to exchange control information. This paper presents a novel medium access control(MAC) protocol for CR network whic...One of the challenging tasks in cognitive radio(CR) networks is to agree on a common control channel to exchange control information. This paper presents a novel medium access control(MAC) protocol for CR network which efficiently and intelligently establishes a common control channel between CR nodes. The proposed protocol is the first CR MAC protocol which is hybrid in nature and lies between global common control channel(GCCC) and non-GCCC family of MAC protocols. The dynamic nature of the protocol makes the CR nodes converge on a newly found control channel quicker whenever the interference from a licensed user is sensed. The analytical results show that the dynamic, hybrid and adaptive nature of proposed protocol yields higher throughputs when compared with other CR MAC protocols.展开更多
Web服务组合可以通过整合网络上现有的多种异构服务从而形成新的服务。针对服务组合中的可靠性和相关性能评估问题,提出了一种基于离散时间马尔可夫链DTMC(Discrete Time Markov Chain)的评估方法。从不同运行场景的角度,利用DTMC相关...Web服务组合可以通过整合网络上现有的多种异构服务从而形成新的服务。针对服务组合中的可靠性和相关性能评估问题,提出了一种基于离散时间马尔可夫链DTMC(Discrete Time Markov Chain)的评估方法。从不同运行场景的角度,利用DTMC相关性质和公式综合估算了服务组合的可靠性和其他性能,并针对具体服务组合的瓶颈进行了分析,提出了改进措施。与现有的服务组合可靠性和性能分析方法相比,本方法对服务组合中结构复杂和运行场景多样化的特点具有更好的适应性,更全面、准确地评估了服务组合的可靠性和相关性能。实验表明,本方法具有良好的分析效果和指导改进的能力。展开更多
针对现有工业信息安全研究主要集中在工业以太网方面,缺少对串行链路协议防护的研究等问题,提出一种基于离散时间马尔可夫链(Discrete Time Markov Chain,DTMC)的工业串行协议状态检测算法。该算法利用工业控制系统(Industrial Control ...针对现有工业信息安全研究主要集中在工业以太网方面,缺少对串行链路协议防护的研究等问题,提出一种基于离散时间马尔可夫链(Discrete Time Markov Chain,DTMC)的工业串行协议状态检测算法。该算法利用工业控制系统(Industrial Control System,ICS)行为有限和状态有限的特征,根据串行链路协议历史流量数据,自动构建ICS正常行为模型——DTMC。模型包含状态事件、状态转移、状态转移概率和状态转移时间间隔等行为信息,使用该模型所包含的状态信息作为状态检测规则集。当检测阶段生成的状态信息与状态检测规则集中的信息不同或偏差超过阈值时,产生告警或拒绝等动作。同时,结合综合包检测(Comprehensive Packet Inspection,CPI)技术来扩大协议载荷数据的可检测范围。实验结果表明,所提算法能有效检测语义攻击,保护串行链路安全,且算法误报率为5.3%,漏报率为0.6%。展开更多
为研究塔台管制员在不同工作负荷下注视转移模式的差异,构建了模拟塔台管制的眼动试验平台,根据航班流量密度设计简单和困难2组试验。利用NASA-TLX量表评价被试者在2组试验中的工作负荷,应用离散时间马尔科夫链(discrete time Markov ch...为研究塔台管制员在不同工作负荷下注视转移模式的差异,构建了模拟塔台管制的眼动试验平台,根据航班流量密度设计简单和困难2组试验。利用NASA-TLX量表评价被试者在2组试验中的工作负荷,应用离散时间马尔科夫链(discrete time Markov chain,DTMC)计算被试者在兴趣区间的注视一步转移概率,利用SPSS软件分析2组试验中被试在各兴趣区组的注视一步转移概率差异性。结果发现:被试者的工作负荷随航班流量密度增大而增大。航班流量密度增大后,被试者在场面监视雷达区内的注视转移显著增加,由场面监视雷达区向空域监视雷达区和指令栏区的注视转移显著减少,在进程单区内的注视转移显著增加。管制员的注意力更容易向能获取更多信息的区域发生转移。展开更多
文摘在嵌入式软件开发早期,为其建立可靠性模型能够尽早发现软件设计中存在的问题,从而节约嵌入式软件开发成本。AADL从软件结构和故障传播两个角度来建立软件可靠性模型,但是AADL的半形式化性质使得基于AADL建立的可靠性模型难以对可靠性、安全性等非功能属性进行严格的分析与验证。形式规格说明语言Z语言具有很强的逻辑描述能力,能够精确表达软件中的各种约束,这使得基于Z语言建立的可靠性模型能够很好地进行严格的分析和验证。因此,考虑到AADL和Z的特征,文中提出了一种将AADL与Z相结合的形式化可靠性模型(embedded software Reliability Model combined with Z and AADL,ZARM),该模型具有AADL的描述能力和Z的精确性。文中给出了ZARM故障模型、结构模型和行为模型的建模方法,并在谓词中描述了与可靠性相关的数据约束。在ZARM模型的基础上,文中提出了一种面向概率的基于DTMC的可靠性评估方法,来对ZARM模型进行可靠性定量评估和分析。最后,通过一个飞行管理系统对应用ZARM模型进行可靠性建模的过程进行了说明,并采用所提评估方法对其进行了可靠性评估。评估结果与文献[19]结果的对比说明了所提方法的正确性和有效性。
文摘In recent times, computer based systems are frequently used for protection and control in the various industries viz Nuclear, Electrical, Mechanical, Civil, Electronics, Medical, etc. From the operating experience of those computer based systems, it has been found that the failure of which can lead to the severe damage to equipments or environmental harm. The culprit of this accident is nobody other than our software, whose reliability has not been ensured in those conditions. Also for real time system, throughput of the system and average response time are very important constructs/ metrics of reliability. Moreover neither of the software reliability model is available which can be fitted generically for all kinds of software. So, we can ensure reliability at the early stage i.e. during design phase by architecturing the software in a better way. The objective of this paper is to provide an overview of the state-of-the-art research in the area of architecture-based software reliability analysis. We then describe the shortcomings and the limiting assumptions underlying the prevalent research. We also propose various approaches which have the potential to address the existing
基金supported by the National Natural Science Foundation of China (60972011)the Research Fund for the Doctoral Program of Higher Education of China (20100002110033)the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University (2011D11)
文摘In anomaly detection, a challenge is how to model a user＇s dynamic behavior. Many previous works represent the user behavior based on fixed-length models. To overcome their shortcoming, we propose a novel method based on discrete-time Markov chains （DTMC） with states of variable-length sequences. The method firstly generates multiple shell command streams of different lengths and combines them into the library of general sequences. Then the states are defined according to variable-length behavioral patterns of a valid user, which improves the precision and adaptability of user profiling. Subsequently the transition probability matrix is created. In order to reduce computational complexity, the classification values are determined only by the transition probabilities, then smoothed with sliding windows, and finally used to discriminate between normal and abnormal behavior. Two empirical evaluations on datasets from Purdue University and AT＆T Shannon Lab show that the proposed method can achieve higher detection accuracy and require less memory than the other traditional methods.
文摘One of the challenging tasks in cognitive radio(CR) networks is to agree on a common control channel to exchange control information. This paper presents a novel medium access control(MAC) protocol for CR network which efficiently and intelligently establishes a common control channel between CR nodes. The proposed protocol is the first CR MAC protocol which is hybrid in nature and lies between global common control channel(GCCC) and non-GCCC family of MAC protocols. The dynamic nature of the protocol makes the CR nodes converge on a newly found control channel quicker whenever the interference from a licensed user is sensed. The analytical results show that the dynamic, hybrid and adaptive nature of proposed protocol yields higher throughputs when compared with other CR MAC protocols.
文摘Web服务组合可以通过整合网络上现有的多种异构服务从而形成新的服务。针对服务组合中的可靠性和相关性能评估问题,提出了一种基于离散时间马尔可夫链DTMC(Discrete Time Markov Chain)的评估方法。从不同运行场景的角度,利用DTMC相关性质和公式综合估算了服务组合的可靠性和其他性能,并针对具体服务组合的瓶颈进行了分析,提出了改进措施。与现有的服务组合可靠性和性能分析方法相比,本方法对服务组合中结构复杂和运行场景多样化的特点具有更好的适应性,更全面、准确地评估了服务组合的可靠性和相关性能。实验表明,本方法具有良好的分析效果和指导改进的能力。
文摘针对现有工业信息安全研究主要集中在工业以太网方面,缺少对串行链路协议防护的研究等问题,提出一种基于离散时间马尔可夫链(Discrete Time Markov Chain,DTMC)的工业串行协议状态检测算法。该算法利用工业控制系统(Industrial Control System,ICS)行为有限和状态有限的特征,根据串行链路协议历史流量数据,自动构建ICS正常行为模型——DTMC。模型包含状态事件、状态转移、状态转移概率和状态转移时间间隔等行为信息,使用该模型所包含的状态信息作为状态检测规则集。当检测阶段生成的状态信息与状态检测规则集中的信息不同或偏差超过阈值时,产生告警或拒绝等动作。同时,结合综合包检测(Comprehensive Packet Inspection,CPI)技术来扩大协议载荷数据的可检测范围。实验结果表明,所提算法能有效检测语义攻击,保护串行链路安全,且算法误报率为5.3%,漏报率为0.6%。
文摘为研究塔台管制员在不同工作负荷下注视转移模式的差异,构建了模拟塔台管制的眼动试验平台,根据航班流量密度设计简单和困难2组试验。利用NASA-TLX量表评价被试者在2组试验中的工作负荷,应用离散时间马尔科夫链(discrete time Markov chain,DTMC)计算被试者在兴趣区间的注视一步转移概率,利用SPSS软件分析2组试验中被试在各兴趣区组的注视一步转移概率差异性。结果发现:被试者的工作负荷随航班流量密度增大而增大。航班流量密度增大后,被试者在场面监视雷达区内的注视转移显著增加,由场面监视雷达区向空域监视雷达区和指令栏区的注视转移显著减少,在进程单区内的注视转移显著增加。管制员的注意力更容易向能获取更多信息的区域发生转移。
