Instance-based domain ontological view creation towards semantic integration

In many domains today there are very limited explicit ontologies established for implementing information systems. Traditional ontology-driven semantic integration approaches cannot be directly applied in integrating these information systems. Usually, the information systems have schemas, a type of formal information model, for their information repositories which to some extent imply the semantics of the information. Each schema actually reflects a specific view of the domain conceptualization. This paper investigates the theoretical foundation of ontologies and extends the traditional ontology concept to the ontological view concept. It proposes to use ontological views to address the challenge of semantic integration. The proposed approach adopts the schemas to create local ontological views, uses data instances of the information systems to discover semantic relationships between the concepts within the ontological views, and builds a domain ontological view based on the discovered equivalence mappings. It applies the hierarchical clustering technique on the data instances and, in the further analysis, uses the clusters to reduce the cost of processing a large amount of data. The matching of concept properties is based on the probability distribution of the data instances. The experimental results have demonstrated the effectiveness of this approach.     

Collaborative design: Improving efficiency by concurrent execution of Boolean tasks

Computer-Aided Design (CAD) applications provide design and engineering professionals with various computer-based tools to perform design activities. As efficiency is one of the most important requirements in most design tasks, in this article, we contribute a novel collaborative design approach to improving efficiency, where a complex design task can be divided and executed concurrently by multiple collaborative designers. This approach is particularly effective for design tasks where Boolean operations – widely supported by most CAD applications – are heavily used in design activities, such as architecture design, mechanical design and digital media design. We have designed and implemented a prototype system CoAutoCAD to test the approach and to demonstrate a variety of collaborative design activities.     

基于交互式马尔可夫链的可信动态度量研究

可信动态度量为保障可信计算平台的可靠运行提供了重要支撑.根据系统的可靠性、可用性、信息和行为安全性,提出了可信度量要达到的目标.当前的可信度量集中在可信功能度量上,基于交互式马尔可夫链增加性能特征指标度量,即在预期行为描述模型中,运用变迁系统模型描述功能预期,通过将体现在可靠性上的路径概率与预期的关联,获取完成特定行为...     

基于CAN总线星务仿真系统的设计与实现

综合考虑研制成本以及卫星在轨运行的可靠性和安全性,使用PCI1680 CAN总线控制卡作为主控节点,模拟小卫星星务系统.系统采用双总线冗余设计来提高可靠性,根据特定的组帧解帧协议实现遥控/遥测功能,同时具备电压采集和电源控制功能,为小卫星系统提供全面、通用的地面测试和调试环境.     

无线传感器网络节点自身定位算法研究

无线传感器网络中节点自身位置信息是实现其应用的最重要因素之一.针对节点自身定位的研究很多,但很大一部分都集中在算法的改进和新算法的开发上,很少给出纵向直观的仿真效果比较.研究选取无需测距算法中4种典型的算法,给出它们在不同参数下的仿真定位效果图,对于工程人员根据实际选取最优算法有很好的借鉴作用.在此基础上,利用曲线拟合...     

A Programming Language Approach to Internet-Based Virtual Computing Environment

There is an increasing need to build scalable distributed systems over the Internet infrastructure. However, the development of distributed scalable applications suffers from lack of a wide accepted virtual computing environment. Users have to take great efforts on the management and sharing of the involved resources over Internet, whose characteristics are intrinsic growth, autonomy and diversity. To deal with this challenge, Internet-based Virtual Computing Environment (iVCE) is proposed and developed to serve as a platform for distributed scalable applications over the open infrastructure, whose kernel mechanisms are on-demand aggregation and autonomic collaboration of resources. In this paper, we present a programming language for iVCE named Owlet. Owlet conforms with the conceptual model of iVCE, and exposes the iVCE to application developers. As an interaction language based on peer-to-peer content-based publish/subscribe scheme, Owlet abstracts the Internet as an environment for the roles to interact, and uses roles to build a relatively stable view of resources for the on-demand resource aggregation. It provides language constructs to use 1) distributed event driven rules to describe interaction protocols among different roles, 2) conversations to correlate events and rules into a common context, and 3) resource pooling to do fault tolerance and load balancing among networked nodes. We have implemented an Owlet compiler and its runtime environment according to the architecture of iVCE, and built several Owlet applications, including a peer-to-peer file sharing application. Experimental results show that, with iVCE, the separation of resource aggregation logic and business logic significantly eases the process of building scalable distributed applications.     

现场总线在冷矫直机辅机控制系统中的应用

本文结合冷矫辅机的电气控制系统,介绍了特殊管厂热处理线冷矫直机辅机的生产工艺,分析了控制系统的工艺流程和需求,着重描述了基于Profibus—DP现场总线的该区域控制系统的结构和调速系统的构成,以及S7—300PLC、ET200M远程I／O站和ATV71系列变频器的通信功能、网络组态和参数设置。通过Profibus—DP数据通信以实现对施耐德ATV71变频器和ET200M的网络化控制,使冷矫辅机的电气控制系统高效地运行。     

SPACE: A lightweight collaborative caching for clusters

In this paper, we introduce Systematic P2P Aided Cache Enhancement or SPACE, a new collaboration scheme among clients in a computer cluster of a high performance computing facility to share their caches with each other. The collaboration is achieved in a distributed manner, and is designed based on peer-to-peer computing model. The objective is to provide (1) a decentralized solution, and (2) a near optimal performance with reasonably low overhead. Simulation results are given to demonstrate the performance of the proposed scheme. In addition, the results show that SPACE evenly distributes work loads among participators, and entirely eliminates any requirement of a central cache manager.     

Health Outcomes and Socio-economic Status Among the Elderly in China: Evidence from the CHARLS Pilot

We are concerned in this paper with measuring health outcomes among the elderly in Zhejiang and Gansu provinces, China, and examining the relationships between different dimensions of health status and measures of socio-economic status (SES). We are CHARLS pilot data to document health conditions, using a very rich set of health indicators that include both self-reported measures and biomarkers. We also examine correlations between these health outcomes and two important indicators of socio-economic status (SES): education and log of per capita expenditure (log pce), our preferred measure of household resources. In general education tends to be positively correlated with better health outcomes, as it is in other countries. However, unmeasured community influences turn out to be highly important, much more so than one usually finds in other countries. While it is not yet clear which aspects of communities matter and why they matter, we set up an agenda for future research on this topic. We also find a large degree of under-diagnosis of hypertension, a major health problems that afflicts the aged. This implies that the current health system is not well prepared to address the rapid aging of the Chinese population, at least not in Gansu and Zhejiang.