Dynamic batching policies for an on-demand video server

In a video-on-demand environment, continuous delivery of video streams to the clients is guaranteed by sufficient reserved network and server resources. This leads to a hard limit on the number of streams that a video server can deliver. Multiple client requests for the same video can be served with a single disk I/O stream by sending (multicasting) the same data blocks to multiple clients (with the multicast facility, if present in the system). This is achieved by batching (grouping) requests for the same video that arrive within a short time. We explore the role of customer-waiting time and reneging behavior in selecting the video to be multicast. We show that a first come, first served (FCFS) policy that schedules the video with the longest outstanding request can perform better than the maximum queue length (MQL) policy that chooses the video with the maximum number of outstanding requests. Additionally, multicasting is better exploited by scheduling playback of the most popular videos at predetermined, regular intervals (hence, termed FCFS-). If user reneging can be reduced by guaranteeing that a maximum waiting time will not be exceeded, then performance of FCFS- is further improved by selecting the regular playback intervals as this maximum waiting time. For an empirical workload, we demonstrate a substantial reduction (of the order of 60%) in the required server capacity by batching.     

新型非织造布经轴染色用打卷退卷机

介绍了新型非织造布经轴染色用打卷退卷机的操作工艺流程、技术原理。说明了根据非织造布经轴染色前后放卷、收卷过程中低张力的要求,应用国内领先电子技术设计的低张力打卷退卷机的性能良好。     

工件加工时间随工件开工时间线性增加的成组排序问题

本文讨论了工件加工时间随工件开工时间线性增加的成组排序问题,考虑的目标函数是最大完工时间,在成组技术假设下得到了最大完工时间问题是多项式时间可解的。     

一种提高电子配料控制器精度的算法研究

在工农业生产过程中,有不少行业如饲料、建材、化工、制药等都需要对生产原料按照一定的比例混合,通过配制加工成产品,这就是配料的过程。高精度、高速度配料对产品质量显然是至关重要的,所以,以单片机作为控制核心的电子配料控制器,以其测量准确度高、性能可靠、成本低廉、体积小和使用范围广等优点,将逐渐代替传统的配料生产线中的称量控制系统在生产领域中发挥越来越重要的作用。     

日产IHI拌和楼混凝土最佳拌和时间试验

位于三峡左岸98．7m的混凝土拌和系统，装有日产强制式2×45001IHI楼。为确保混凝土拌和系统质量，曾进行过多项参教试验，在混凝土中既要掺粉煤灰，又要掺复合剂，还要接碎冰。为探索生产这种混凝土拌和物的均匀性与其最佳拌和时间，进行了拌和物在不同拌和时间下的考核、混凝土测温试验、坍落度试验和含气量试验。结果表明，拌和时间延长至110s为最佳拌和时间。     

订单分批算法的适用性研究

本文回顾了当前企业分拣过程中订单分批的最优算法.在人工分拣环境,在不同储位分配和仓储物品量的条件下,对订单分批的FIFS,MAA,COG,GSM,GS等五种算法进行考察.根据某国有大型企业的订单数据和计算机生成订单,采用Java编程实现各种算法,通过程序分析了不同条件下各种算法的分拣效率.实验结果表明S型分拣路线的MAA启发式算法,比其他算法优化效果更好,因此推荐采用.     

Proxy-based patching stream transmission strategy in mobile streaming media system

A mobile transmission strategy, PMPatching （Proxy-based Mobile Patching） transmission strategy is proposed, it applies to the proxy-based mobile streaming media system in Wideband Code Division Multiple Access （WCDMA） network. Performance of the whole system can be improved by using patching stream to transmit anterior part of the suffix that had been played back, and by batching all the demands for the suffix arrived in prefix period and patching stream transmission threshold period. Experimental results show that this strategy can efficiently reduce average network transmission cost and number of channels consumed in central streaming media server.     

Two-stage hybrid batching flowshop scheduling with blocking and machine availability constraints using genetic algorithm

This research investigates a two-stage hybrid flowshop scheduling problem in a metal-working company. The first stage consists of multiple parallel machines and the second stage has only one machine. Four characteristics of the company have substantiated the complexity of the problem. First, all machines in stage one are able to process multiple jobs simultaneously but the jobs must be sequentially set up one after another. Second, the setup time of each job is separated from its processing time and depends upon its preceding job. Third, a blocking environment exists between two stages with no intermediate buffer storage. Finally, machines are not continuously available due to the preventive maintenance and machine breakdown. Two types of machine unavailability, namely, deterministic case and stochastic case, are identified in this problem. The former occurs on stage-two machine with the start time and the end time known in advance. The latter occurs on one of the parallel machine in stage one and a real-time rescheduling will be triggered. Minimizing the makespan is considered as the objective to develop the optimal scheduling algorithm. A genetic algorithm is used to obtain a near-optimal solution. The computational results with actual data are favorable and superior over the results from existing manual schedules.     

一种基于现场总线及分布式I/O控制的混凝土搅拌站设计

利用现场总线及分布式I/O控制技术设计一种新型混凝土搅拌站。通过总线和分布式I/O技术,使得混凝土搅拌站的控制系统更利于功能的升级、扩展,同时也便于工作人员进行排故与检修,大大增强了系统运行的稳定性。     

顺序输送管道混油问题的研究

对顺序输送管道影响混油的因素进行了讨论。针对顺序输送管道中控制混油的问题 ,在保证油品质量的前提下 ,根据现场实测数据 ,对混油量的估计和选择合理混油处理方案作了研究。并且对混油率的定义提出了自己的观点