Similarity based mixed transaction concurrency control protocol

1 Introduction 1 Real-Time database applications, such as stock trading systems, telecommunication managements, and air traffic management are characterized by large volume of data as well as time constrained data access [1]. The correctness of such applications depends on both execution results and time constraints imposed on transaction commitments, generally in terms of deadline. Based on the different consequences of deadline missing, transactions in a real-time database systems (RTDBS) …     

弱可串行分布式实时事务并发控制

Most of the proposed concurrency control protocols for real-time database systems are based on serializability theorem.Owing to the unique characteristics of real-time database applications and the importance of satisfying the timing constraints of transactions,serializability is too strong as a correctness criterion and not suitable for real-time databases in most cases.On the other hand,relaxed serializability including epsilon-serializability and similarity-serializability can allow more real-time transactions to satisfy their timing constraints,but database consistency may be sacrificed to some extent.We thus propose the use of weak serializability(WSR)that is more relaxed than conflicting serializability while database consistency is maintained.In this paper,we first formally define the new notion of correctness called weak serializability.After the necessary and sufficient conditions for weak serializability are shown,corresponding concurrency control protocol WDHP(weak serializable distributed high prority protocol)is outlined for distributed real time databases,where a new lock mode called mask lock mode is proposed for simplifying the condition of global consistency.Finally,through a series of simulation studies,it is shown that using the new concurrency control protocol the performance of distributed realtime databases can be greatly improved.     

Study on Mandatory Access Control in a Secure Database Management System

This paper propses a security policy model for mandatory access control in class B1 database management system whose level of labeling if tuple.the relation-hierarchical data model is extended to multilevel relation-hierarchical data model.Based on the multievel relation-hierarchical data model,the concept of upper-lower layer relational integrity is presented after we analyze and eliminate the covert channels caused by the database untegrity,Two SQL statements are extended to process polyinstantiation in the multilevel secure environment.The system is based on the multievel relation-hierarchical data model and is capable of integratively storing and manipulating multilevel complicated objects(e.g.,multilevel spatial data) and multievel conventional data(e.g.,integer,real number and character string).     

信息系统可靠性管理研究

An integrated intelligent management is presented to help organizations manage many heterogeneous resources in their information system. A general architecture of management for information system reliability is proposed, and the architecture from two aspects, process model and hierarchical model, described. Data mining techniques are used in data analysis. A data analysis system applicable to real-time data analysis is developed by improved data mining on the critical processes. The framework of the integrated management for information system reliability based on real-time data mining is illustrated, and the development of integrated and intelligent management of information system discussed.     

Real-time temperature control for high arch dam based on decision support system

It is important and difficult to control the temperature of mass concrete structure during high arch dam construction.A new method with decision support system is presented for temperature control and crack prevention.It is a database system with functions of data storage,information inquiry,data analysis,early warning and resource sharing.Monitoring information during construction can be digitized via this system,and the intelligent analysis and dynamic control of concrete temperature can be conducted.This method has been applied in the construction of the Dagangshan Arch Dam in China and has proven to be very convenient.Based on the decision support of this system and the dynamic adjustment of construction measures,the concrete temperature of this project is well-controlled.     

Adaptive XML to relational mapping： an integrated approach

Storing and querying XML （eXtensible Markup Language） data in relational form can exploit various services offered by modern relational database management systems （RDBMSs）. Due to structural complexity of XML, there are many equivalent relational mapping schemes for the same XML data and queries. In this paper, we propose the adaptive XML to relational mapping （AX2RM） system, which considers finding optimal XML to relational （X2R） mapping as four separate but correlated procedures： logical database design, data scale estimation, workload transformation, and physical database design. We view the whole process as an autonomic computing problem and formalize the adaptive X2R mapping problem. Search spaces for each procedure are investigated individually, and five approaches for finding the optimal mapping are studied. We propose an integrated approach with greedy pruning （IT-GP）, which views the mapping procedures as a whole and exploits heuristic rules in each procedure to prune impossible mappings as early as possible. Evaluation of these approaches shows the validity and high efficiency of IT-GP.     

Discrete optimization models and methods for management systems of pavement maintenance and rehabilitation

With the rapid development of highway construction and formation of the highway network in China,the man- agement of pavement maintenance and rehabilitation （MR） activities has become important.In this paper,four discrete optimization models are proposed for different parties involved in the management system： government,highway agent,con- tractor and the common users.These four optimal decision models are formulated as linear integer programming problems with binary decision variables.The objective function and constraints are based on the pavement performance and prediction model using the pavement condition index （PCI）.Numerical experiments are carried out with the data from a highway system in Sichuan Province which show the feasibility and effectiveness of the proposed models.     

以太无源光网络接入控制器的实现

1IntroductionWith the developing of packet switching and trans-mission technologies,many IP-oriented applicationshave experienced a substantial growth,makingit pos-sible for various real-ti me broadband video servicesviathe Internet.However,current access networktechnologies can only offer512k-2M subscriberbandwidth,whichis unable to meet the broadband de-mand of emerging3Tnet services such as high-defini-tion video(HDTV)and real-ti me network TV broad-cast.Therefore,the access network sti…     

Construction of life cycle assessment software system platform

There has not been life cycle assessment (LCA) software applicable to China's products. To faciliate the development of LCA software system in China, we built an object-oriented LCA software system plantform based on LCA international standards ISO 14040 to ISO 14043 and the commonness of diverse products. The system includes six modules: disassembly module, data collection module, arithmetic module, drawing module, database module and control module. It evaluates all economic and environmental impacts during the whole life cycle of a product. The integrated life cycle inventory database system allows dynamic expansion, which makes the effort required for data collection reduce with the increase of the system's application. With the improvement of human environmental-awareness, the demand of environment-friendly products is increasing, and ecological design of products has become a critical part in products development. Consummation of the LCA software system will provide a powerful tool for designing and developing Chinese ecological products.     

FlexRay时钟同步拜占庭故障容错算法研究

为了解决FlexRay分布式实时系统中时钟同步可能出现拜占庭故障,从而导致系统时钟崩溃的问题,提出一种有效的解决算法FlexRayBFT （FlexRay Byzantine-Fault-Tolerant）。该算法在传统拜占庭容错算法基础上引入消息认证码技术,对报文进行加密处理,相比指数型算法,其性能提高了3个数量级。FlexRayBFT执行分为准备阶段与回复执行阶段,分析不同阶段的消息具体通信过程,同时证明了算法的一致性与正确性。通过使用Truetime工具箱搭建FlexRay线控转向分布式实时系统,对系统使用FlexRayBFT算法前后分别进行仿真实验验证。结果表明,FlexRayBFT算法可以有效克服FlexRay分布式实时系统中时钟同步的拜占庭故障,保障时钟同步的稳定性。     

实时内存数据库存储结构及数据安置策略

给出了实时内存数据库的定义、存储结构和数据特征,在此基础上,提出了一个合理的数据安置策略,引入了存储类的概念,使系统能够有效利用有限的内存空间,提高系统的性能。     

在线交易情境下整合与分离定价模式的研究与思考

电子商务的发展与繁荣,在线交易中的定价问题日益突出,相关研究也逐渐成为学术界极具创新性和挑战性的课题.当前,在线交易情境下的定价模式普遍涉及整合定价和分离定价两个方面,文中尝试从理论视角、基本变量关系、调节效应等方面对国内外学者关于在线交易中整合与分离定价的研究成果进行了梳理和分析,并围绕研究主题、研究视角和研究方法3个方面对未来可能的研究方向提出了思考.     

MIC商用并行编程性能优化分析

针对MIC架构处理各种复杂业务时对性能日益增长的要求,为充分利用MIC使用已有编程模型的优势,通过避免内存容量、网络带宽方面的瓶颈增强并行编程的线程扩展性,对并行度、内存空间、数据通信与传递、Cache访问、负载均衡以及循环分块和向量化等方法进行了讨论。通过在内存数据库领域优化性能的应用,对使用三层优化方法发挥MIC众核技术优势进行了分析与展望。     

基于并行FP-growth算法挖掘网上关联交易规则

发现关联规则是数据挖掘技术的重要任务之一。之前提出的绝大多数算法需要多次遍历数据库才能产生频繁项集,造成巨大的CPU和内存开销。根据网上交易数据海量的特点,提出了一种基于频繁模式增长(FP-growth)的并行算法。该算法可以在不产生候选集的基础上并行的挖掘海量数据。试验证明该算法可以缓解了项目数量巨大而内存不足的矛盾,减少了算法的执行时间。利用该算法对网上交易进行关联规则挖掘,发现了有价值的决策支持信息。     

双操作系统任务调度策略及其改进简

双操作系统是虚拟机运行在主操作系统,然后通过虚拟机来运行从操作系统.从操作系统的任务调度只能等到主操作系统任务调度空闲才能调度.导致不能及时响应高优先级别的任务,系统容易崩溃.因此如果先运行虚拟机,再运行主从操作系统,最后通过虚拟机来调度主从操作系统任务,同时改进双操作系统间的任务调度策略.那么就能保证整个双操作系统任务之间的平滑调度,从而使整个系统稳健可靠运行.     

一种车联网多跳视频传输实验系统的设计与实现(英文)

提出一种在车辆自组织网络(VANET)中应用的无线多跳视频传输实验系统的设计和实现方案及其对应的传输控制和路由选择协议.该系统将嵌入式Linux与IEEE 802.11n传输协议集成到ARM内核,由S3C6410主控模块、无线局域网网卡及LCD屏等构成.针对VANET的无线多跳视频传输场景,对视频编译码分别采用H.264和JPEG两种标准实现并对它们的压缩比、时延、传输丢包率等性能进行了理论分析和实验比较,进行了室内室外多种不同场景的实际测试.结果表明:所设计的多跳视频传输实验系统方案能够适应VANET等多种场景的应用,所提出的传输控制和路由选择协议能够保证视频传输的多跳和实时性要求.     

SQL网络数据库的安全性研究

网络数据库的安全可以保证考试信息的保密性、完整性、一致性和可用性,因此系统管理员必须重视服务器端的安全性设置并不断探索SQL网络数据库的安全性策略。