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41.
提出一种借助系统调用实现基于信息流的完整性度量的方法。该方法将度量过程分为离线阶段和运行阶段。在离线阶段,软件执行的系统调用被监控和记录,结合系统调用和信息流的关系抽象出软件的信息流基准值。在运行阶段,分析软件运行时的系统调用信息,获得软件运行时的信息流,根据信息流基准值检查软件的信息流是否出现异常,度量软件的完整性。为了验证方法的可行性,文章以Apache服务器为例,实现该方法的原型系统。实验表明该方法能够发现软件运行时完整性被破坏而出现的异常信息流。  相似文献   
42.
In this paper, we present a typical temporal partitioning methodology that temporally partitions a data flow graph on reconfigurable system. Our approach optimizes the communication cost of the design. This aim can be reached by minimizing the transfer of data required between design partitions and the routing cost between FPGA modules. Consequently, our algorithm is composed by two main steps. The first step aims to find a temporal partitioning of the graph. This step gives the optimal solution in term of communication cost. Next, our approach builds the best architecture, on a partially reconfigurable FPGA, that gives the lowest routing cost between modules. The proposed methodology was tested on several examples on the Xilinx Virtex-II pro. The results show significant reduction in the communication cost compared with others famous approaches used in this field.  相似文献   
43.
Certain behavioral properties of distributed systems are difficult to express in interleaving semantics, whereas they are naturally expressed in terms of partial orders of events or, equivalently, Mazurkiewicz traces. Two examples of such properties are serializability of a database and global snapshots of concurrent systems. Recently, a modest extension for LTL by an operator that expresses snapshots, has been proposed. It combines the ease of linear (interleaving) specification with this useful partial order concept. The new construct allows one to assert that a global snapshot appeared in the past, perhaps not in the observed execution sequence, but possibly in an equivalent one.  相似文献   
44.
This paper introduces the concept of the temporal think tank™ (T3™), a temporary in-house research center, based on case studies with a highly automated global manufacturer and in various small-sized manufacture (SME's). The T3™ brings individuals from across the organization together in a team setting in which they are charged to look at the future, develop their decision-making skills, and use entrepreneurial thinking to incubate new processes and/or products. After an appropriate time in the temporal think tank™, the individuals are asked to return to their regular positions to implement the best practices and best ideas and doing so spur the organization forward. At intervals, the temporal think tanks™ can be reconvened, or reconstituted with new participants. This approach prepares technology champions for the SME, who can return to the organization with a fresh outlook and renewed energy to keep the enterprise at the peak of efficiency and effectiveness.  相似文献   
45.
工控网络安全态势感知算法实现   总被引:1,自引:0,他引:1  
为了探知工控系统的网络安全态势,准确判断系统运行状况,提出了安全态势感知方法.针对已有的完整性攻击研究,建立基于拜占庭将军问题的工控网络安全态势感知模型以及相应的安全态势感知算法.本文提出的算法主要通过三个部分实现:首先对控制回路内的各节点信息进行采集与处理,得到系统中各节点状态;然后,利用所得节点状态,执行算法流程,确定系统内存在的恶意节点;最终获取准确的工控网络安全态势.实验结果表明:该态势感知模型与算法能准确提炼系统中的恶意节点并判断当前系统安全态势.  相似文献   
46.
The California sage scrub (CSS) community type in California's Mediterranean-type ecosystems is known for its high biodiversity and is home to a large number of rare, threatened, and endangered species. Because of extensive urban development in the past fifty years, this ecologically significant community type is highly degraded and fragmented. To conserve endangered CSS communities, monitoring internal conditions of communities is as crucial as monitoring distributions of the community type in the region. Vegetation type mapping and field sampling of individual plants provide ecologically meaningful information about CSS communities such as spatial distribution and species compositions, respectively. However, both approaches only provide spatially comprehensive information but no information about internal conditions or vice versa. Therefore, there is a need for monitoring variables which fill the information gap between vegetation type maps and field-based data. A number of field-based studies indicate that life-form fractional cover is an effective indicator of CSS community health and habitat quality for CSS-obligated species. This study investigates the effectiveness of remote sensing approaches for estimating fractional cover of true shrub, subshrub, herb, and bare ground in CSS communities of southern California. Combinations of four types of multispectral imagery ranging from 0.15 m resolution scanned color infrared aerial photography to 10 m resolution SPOT 5 multispectral imagery and three image processing models - per-pixel, object-based, and spectral mixture models - were tested.An object-based image analysis (OBIA) routine consistently yielded higher accuracy than other image processing methods for estimating all cover types. Life-form cover was reliably predicted, with error magnitudes as low as 2%. Subshrub and herb cover types required finer spatial resolution imagery for more accurate predictions than true shrub and bare ground types. Positioning of sampling grids had a substantial impact on the reliability of accuracy assessment, particularly for cover estimates predicted using multiple endmember spectral mixture analysis (MESMA) applied to SPOT imagery. Of the approaches tested in this study, OBIA using pansharpened QuickBird imagery is one of the most promising approaches because of its high accuracy and processing efficiency and should be tested for more heterogeneous CSS landscapes. MESMA applied to SPOT imagery should also be examined for effectiveness in estimating factional cover over more extensive habitat areas because of its low data cost and potential for conducting retrospective studies of vegetation community conditions.  相似文献   
47.
ADS5287及其在MIMO接收机中的应用   总被引:1,自引:1,他引:0  
介绍了TI公司模数转换器ADS5287的性能特点.用ADS5287作为模数转换器设计了MIMO中频接收机电路,完成了系统的PCB设计,并使用Hyperlynx软件中的Boradsim工具对设计中重要的高速信号线做了信号完整分析.  相似文献   
48.
The modal μ-calculus is a very expressive temporal logic. In particular, logics such as LTL, CTL and CTL* can be translated into the modal μ-calculus, although existing translations of LTL and CTL* are at least exponential in size. We show that an existing simple first-order extension of the modal μ-calculus allows for a linear translation from LTL. Furthermore, we show that solving the translated formulae is as efficient as the best known methods to solve LTL formulae directly.  相似文献   
49.
本文给出了一个基于查询的关系模式(RDB)到XML模式转换的新算法。分析了查询模式,并且通过列间的相等合并来抽出隐式参照完整性。该算法不仅反映了外在参照完整性,还反映了RDB到XML的隐式参照完整性。  相似文献   
50.
Predictive modelling of online dynamic user-interaction recordings and community identification from such data becomes more and more important with the widespread use of online communication technologies. Despite of the time-dependent nature of the problem, existing approaches of community identification are based on static or fully observed network connections. Here we present a new, dynamic generative model for the inference of communities from a sequence of temporal events produced through online computer- mediated interactions. The distinctive feature of our approach is that it tries to model the process in a more realistic manner, including an account for possible random temporal delays between the intended connections. The inference of these delays from the data then forms an integral part of our state-clustering methodology, so that the most likely communities are found on the basis of the likely intended connections rather than just the observed ones. We derive a maximum likelihood estimation algorithm for the identification of our model, which turns out to be computationally efficient for the analysis of historical data and it scales linearly with the number of non-zero observed (L + 1)-grams, where L is the Markov memory length. In addition, we also derive an incremental version of the algorithm, which could be used for real-time analysis. Results obtained on both synthetic and real-world data sets demonstrate the approach is flexible and able to reveal novel and insightful structural aspects of online interactions. In particular, the analysis of a full day worth synchronous Internet relay chat participation sequence, reveals the formation of an extremely clear community structure.  相似文献   
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