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并发控制是改善数据库系统性能的最重要的机制,在XML数据管理中并发控制已经成为一个重要的研究课题。本文给出了一种基于XPath路径查询语言的XML数据库并发控制机制,主要包括:定义了XPLock锁协议模型以及锁协议规则,讨论了并发控制操作流程,给出了死锁的检测与处理方案和事务撤销与中止的处理方法。 相似文献
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替代和补偿是实时事务的两个基本特点,也是并发控制的主体,同时给并发控制带来了新的问题。AC-Based OCC-FV协议把替代和补偿综合到乐观并发控制协议OCC-FV中来,对于处于接纳队列中的每个事务,尽可能地选择无冲突替代进入就绪队列,但这只是一个理想情况。如果冲突不可避免,不仅要选择一个合适替代参与并发控制,即使冲突发生时,也要确保系统始终处于一个安全状态。在冲突消解时,结合补偿的特点,对乐观并发控制协议OCC-FV进行了扩展,当事务失败后,立即调度相应补偿事务,以防止系统灾难的发生。 相似文献
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在事务并发访问数据库的过程中,锁是数据库完整性和一致性的重要保证.通过对SQL Server 2000锁机制的分析,介绍了数据库锁、多粒度性及锁的模式、兼容性,对死锁问题进行分析,提出了死锁的一些防止方法. 相似文献
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本文主要是把替代引入到乐观并发控制协议OCC-WAIT50中来,提出了一种实时并发控制协议A-BasedOCC-WAIT50。由于各替代的资源需求不同,所以,参与资源竞争受阻的机会也不同。对于处于接纳队列中的事务,选择一个最优替代参与并发控制,可以避免或减少冲突的发生。而当冲突不可避免时,再采用乐观并发控制协议OCC-WAIT50进行冲突消解。 相似文献
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通过用户访问事务的方式将用户访问Web站点行为进行形式化描述。进一步给出了兴趣度、相似度、聚类中心的定义。提出了基于ISODATA算法的路径聚类方法。并通过对某实际网站Web日志文件进行分析实验,结果表明该方法不但能够发现群体用户访问模式,而且还能得到较为合理的模式聚类个数。 相似文献
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针对知识发现中的模糊信息查询问题，提出了一种基于反馈网络的模糊概念聚类及模式联想设计方法。首先按照分类要求对所要查询的概念集合进行量化编码，然后对编码后的数据进行规整处理。对于概念聚类采用多层反馈神经网络的FP聚类算法，而概念联想采用白反馈神经网络的椭球学习算法实现。将基于上述算法开发出的信息模糊查询系统应用于图书信息查询，实验结果征明了该方法的有效性。 相似文献
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针对知识发现中的信息模糊查询问题，提出了一种基于神经网络的信息聚类及联想实现方法。首先按照信息分类对所要查询的信息进行量化编码，然后对编码后的数据进行规整处理。对于信息聚类采用均值聚类算法，而信息联想采用Hopfield网络实现。将基于上述算法开发出的信息模糊查询系统应用于图书信息查询，实验结果证明了该方法的有效性。 相似文献
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文本聚类算法的质量评价 总被引：4，自引：0，他引：4
文本聚类是建立大规模文本集合的分类体系实例的有效手段之一。本文讨论了利用标准的分类测试集合进行聚类质量的量化评价的手段，选择了k-Means聚类算法、STC（后缀树聚类）算法和基于Ant的聚类算法进行了实验对比。对实验结果的分析表明，STC聚类算法由于在处理文本时充分考虑了文本的短语特性，其聚类效果较好；基于Ant的聚类算法的结果受参数输入的影响较大；在Ant聚类算法中引入文本特性可以提高聚类结果的质量。 相似文献
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实时数据库系统中的事务具有显示的时间约束,因此,与传统的数据库系统相比,实时数据库系统并发控制协议有了一定的扩展。在分析实时数据库系统中实时事务并发执行的新特点的基础上,介绍了几种典型的实时数据库并发控制协议。 相似文献
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空间通信网中音视频传输的应用层QoS控制与测试方法 总被引：1，自引：0，他引：1
分析了无线局域网、因特网和Ku频段卫星通信网的互联互通及服务质量(QoS)性能参数,采用视频帧率、分辨率自适应算法,提出了一种空间通信网中音视频传输的应用层QoS控制与测试方法.仿真实验结果表明,该方法提高了网络利用率,并具有良好的QoS自适应帧率调整能力. 相似文献
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在FDM算法的基础上,提出了一种改进的并行关联规则挖掘算法FDM_DT,此算法利用DHP算法中的Hash表技术改进了2阶侯选项集的生成过程,并采用Apriori Tid算法中的Tid表技术对事务数据库中的事务数进行有效消减。因此,此算法在处理大规模数据时有较高的综合效率。 相似文献
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城市道路人行横道是除交叉口外的重要的交通冲突区域,协调人行横道处的机动车流和行人过街等非机动车流的行为冲突具有重要意义。针对目前人行横道行人过街组织方式存在的弊端,采用基于行人过街请求的主辅灯信号联动控制策略控制人行横道交通行为。首先提出了主辅灯信号系统的辅灯控制方法原理;其次研究基于行人过街请求和主灯控制器信号配时的信号控制策略,实现满足行人过街请求前提下的车辆通行最优化控制方法;最后设计一种行人过节请求的辅灯控制器,通过设计相应功能模块,实现辅灯信号控制策略。模拟实验方案结果表明:在不同信号状态下触发行人过街请求信息,辅灯控制策略模型能够准确输出的辅灯信号的配时方案,在实施该信号控制策略后,车辆通过交叉口和辅灯人行横道区域的通行效率明显增加。 相似文献
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While it is well-known that cross-cultural conflict management is a common problem in multinational joint ventures. The cooperation parties come from different countries and regions, and their social, political and legal systems and cultural backgrounds are different, which leads to the differences in business philosophy, decision-making thinking preferences and management communication modes. The conflict of managerial values caused by cultural differences will inevitably affect the management concept and mode of joint ventures, which will permeate the whole process of enterprise management activities. Employees from different cultural backgrounds may have different acceptance of the rules and regulations of the joint venture or different understanding of the work tasks, which may cause employees′ uncertainty or anxiety and ultimately affect their work innovation behavior and enterprise performance.
However, a fact that can not be ignored is that managers of joint ventures do not know much about cultural differences, the impact of communication modes and how to influence employees′ work innovative behavior. Managers need to manage cultural conflicts and differences between the two countries and even more countries in order to maximize cultural integration and enhance working enthusiasm and creativity of employees. So, this study attempts to reveal the deep-seated impact mechanism of cultural differences between parent company and subsidiary companies and management communication modes on employees′ work innovative behavior. And we also hope to explore the optimal communication mode in cross-cultural conflict management of joint ventures, so as to provide experience for cross-cultural conflict management of joint ventures.
This paper took 211 employees of 12 automobile joint ventures as the research object. Cultural differences perceived by employees were viewed as the independent variable, and communication modes between managers and subordinates were regarded as both independent variables and moderating variables. The theory of anxiety/uncertainty management was adopted to analyze the effect and mechanism of employees′ perceptions of cultural differences on their work innovative behavior. The theory and techniques of Transactional Analysis were used to classify the communication modes between managers and subordinates. The hierarchical regression method was conducted to analyze the samples and compare the impact of different communication modes on employees′ innovative behavior.
Through empirical research, this study mainly draws the following conclusions: (1) Joint venture employees′ perceptions of cultural differences between parent and subsidiary companies affects their innovative behavior. The more cultural differences perceived by employees between parent and subsidiary companies, the more difficult it is for employees to understand the rules and regulations and normative requirements of joint ventures, thus enhancing the risk defense mechanism of employees and curbing their creative and innovative motivation in the process of work. (2) Manager-employee value conflict caused by cultural differences runs through the communication modes between managers and employees, thus affecting the innovative behavior of employees. The three dimensions of communication mode (complementary transactions, crossed transactions and covert ulterior) affect the direction and intensity of employees′ innovative behavior differently. Among them, complementary transactions positively affects employees′ innovative behavior, while crossed transactions and covert ulterior negatively affect employees′ innovative behavior. (3) Different communication modes adopted by manager-employee in the process of communication can moderate the impact of cultural differences perceived by employees on their innovative behavior. Among them, complementary transactions can weaken the negative relationship between employees′ perceptions of cultural differences and their innovative behavior, while covert ulterior strengthens the negative relationship between employees′ perceptions of cultural differences and their innovative behavior, while crossed transactions has no obvious moderating effect.
The theoretical contributions of this study are mainly embodied in the following aspects. Firstly, this study confirms the impact of employees′ perceptions of cultural differences and communication modes between managers and employees on employees′ innovative behavior. Different communication modes between managers and employees will not only directly affect employees′ innovative behavior, but also moderate the relationship between employees′ perceptions of cultural differences and their innovative behavior. Secondly, this study reveals the complex mechanism of the relationship between employees′ perceptions of cultural differences and their innovative behavior, and identifies the important moderating role of different communication modes. Thirdly, this study enriches the application fields of the anxiety/uncertainty theory, and expands the research fields of the theory and techniques of Transactional Analysis.
The results of this study have important reference significance for the management practice of joint ventures. Based on the results of this study, the employees′ perceptions of cultural differences are important factors to affect employees′ innovative behavior. Therefore, we put forward the following management suggestions for joint ventures. Firstly, it is suggested that joint ventures should attach great importance to alleviating the uncertainty and anxiety caused by employees′ perceptions of cultural differences, strive to create a safe and harmonious working environment for employees, so as to stimulate their innovative potential and improve their work enthusiasm and creativity. Secondly, joint ventures should popularize the theory of Transactional Analysis and the techniques of Interpersonal Communication Interaction Analysis in the process of human resources training. In addition, managers and employees of joint ventures should choose appropriate communication modes. When communicating, both managers and employees should give priority to complementary transactions, avoiding the use of crossed transactions and covert ulterior.
However, this study still has the following limitations: (1) This study took the employees of automobile joint ventures in China as research object. The representativeness of the samples needs to be improved. The universality of the research conclusions needs to be confirmed further. (2) There are some inconsistencies between self-evaluation and supervisor-evaluation of employees′ innovative behavior. The supervisor-evaluation data did not verify all the theoretical hypotheses. (3) The richness of the models needs to be strengthened. This study used the theory of anxiety/uncertainty management to explain the main effect of perceptions of cultural differences on employee innovative behavior, and tested the moderating effect of communication modes, but did not explore and test the mediating effect of the relationship between perceptions of cultural differences and employee innovative behavior. We will further explore the mediating variables and effects in the future study. 相似文献
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企业内部冲突的协同进化分析方法 总被引：2，自引：0，他引：2
企业的内部冲突是企业发展过程中面临的重要问题，企业的决策往往是企业内部冲突各方利益协调的结果。以往对企业内部冲突的分析多采用博弈论方法进行，局限性较大，不适合作多博弈方、多目标冲突分析。本文将协同进化思想应用到冲突分析中，建立相应的冲突分析模型，给出模型求解算法，能有效地解决冲突分析中存在的不足。该方法尤其适合于冲突方较多、各方关心的指标较多的情况，通过协调冲突各方。在企业整体利益得到基本保障的前提下。企业内部各方也能达到满意，从而兼顾了企业的眼前利益和长远发展。 相似文献