基于自适应心跳算法的分布式系统故障检测器

故障检测是容错分布式系统中的关键技术之一.为了提高故障检测的性能,提出一种新型的故障检测器——自适应心跳检测器(SA-HD,Self-Adaptive Heartbeat Detec-tor).SA-HD采用了基于拉式(pull)的自适应心跳算法,在考虑故障检测性能的同时也考虑了心跳检测所占用的网络资源对网络性能的影响.SA-HD能够根据网络负载调节自身发送心跳消息的频率,提高了心跳检测的网络环境适应能力,尤其是在高负载的环境下,能够有效改善心跳检测的性能.建立了SA-HD的模型,对其性能进行了仿真分析,并通过试验验证了SA-HD性能要优于传统推式(push)的心跳检测器.

覆盖多播节点失效检测的分布式算法的改进

覆盖多播在端系统间构建数据分发树.由于端系统随意地加入或退出多播组,其可靠性不如路由器.当分发树中的非叶节点退出或者节点失效时,其下游节点将受到影响.低代价而快速的节点失效检测能降低由于服务间断所带来的影响,同时也为后续的恢复工作提供一个良好的基础.在分析相关工作的基础上,提出了一种改进的节点失效检测机制,它能够兼顾节点失效检测时间和额外消息负载两个性能指标.

业务锁机制在医院信息系统中的研究与应用

医院信息系统的一个重要分支是医嘱传输系统,它以医嘱为核心并结合业务流思想。业务锁是协调系统中业务流程与诊疗活动并发性的必要机制,但设计不良的锁会在医嘱流动中引发对核心业务的互锁和死锁,银行家算法及动态检测等技术可以抑制或避免死锁的发生。对业务互锁的研究能有效解决锁定机制与作业流程之间的冲突。

Sequential Similarity Detection Algorithm Based on Image Edge Feature

This paper proposes a new sequential similarity detection algorithm(SSDA), which can overcome matching error caused by grayscale distortion; meanwhile, time consumption is much less than that of regular algorithms based on image feature. The algorithm adopts Sobel operator to deal with subgraph and template image, and regards the region which has maximum relevance as final result. In order to solve time-consuming problem existing in original algorithm, a coarse-to-fine matching method is put forward. Besides, the location correlation keeps updating and remains the minimum value in the whole scanning process, which can significantly decrease time consumption. Experiments show that the algorithm proposed in this article can not only overcome gray distortion, but also ensure accuracy. Time consumption is at least one time orders of magnitude shorter than that of primal algorithm.