Z型管成品油顺序输送混油量数值计算

针对管道输送成品油时的混油量计算问题,采用多相流模型,建立顺序输送混油控制方程,采用有限体积法进行了数值求解。以0#柴油和90#汽油为输送介质,对成品油由上至下和由下至上流经Z型管的2种情况进行了数值计算。研究结果表明,成品油流经Z型管水平管段时,相对于管轴混油段呈不对称分布;在竖直管段,柴上汽下运行时混油量比柴下汽上运行时大;前汽后柴运行时截面的体积分数分布比前柴后汽运行时均匀。     

复杂固态物料自动配料系统研究与开发

本文针对复杂的固态物料如小颗粒状或块状物料的在线自动配料系统进行研究,并开发了一套基于PLC的自动配料系统。该系统既能解决粉末状物料的自动配料问题,又能解决颗粒状和小块状物料的自动配料问题。     

视频点播系统中Batching调度方案的一种改进实现

节目调度是视频点播系统设计与实现的一个重要问题。本文首先对视频点播系统中的节目调度方案作了探讨,然后提出一种Batching调度方案的改进实现方法。理论与实验证明,该方法可以有效地提高视频点播系统的服务水平。     

Multicast video-on-demand service in an enterprise network with client-assisted patching

Multicast Video-on-Demand (VoD) systems are scalable and  cheap-to-operate. In such systems, a single stream is shared by a batch of common user requests. In this research, we propose multicast communication technique in an Enterprise Network where multimedia data are stored in distributed servers. We consider a novel patching scheme called Client-Assisted Patching where clients’ buffer of a multicast group can be used to patch the missing portion of the clients who will request the same movie shortly. This scheme significantly reduces the server load without requiring larger client cache space than conventional patching schemes. Clients can join an existing multicast session without waiting for the next available server stream which reduces service latency. Moreover, the system is more scalable and cost effective than similar existing systems. Our simulation experiment confirms all these claims.

On pricing algorithms for batched content delivery systems

Businesses offering video-on-demand (VoD) and downloadable-CD sales are growing in the Internet. Batching of requests coupled with a one-to-many delivery mechanism such as multicast can increase scalability and efficiency. There is very little insight into pricing such services in a manner that utilizes network and system resources efficiently while also maximizing the expectation of revenue. In this paper, we investigate simple, yet effective mechanisms to price content in a batching context. We observe that if customer behavior is well understood and temporally invariant, a fixed pricing scheme can maximize expectation of revenue if there are infinite resources. However, with constrained resources and potentially unknown customer behavior, only a dynamic pricing algorithm can maximize expectation of revenue. We formulate the problem of pricing as a constrained optimization problem and show that maximizing the expectation of revenue can be intractable even when the customer behavior is well known. Since customer behavior is unlikely to be well known in an Internet setting, we develop a model to understand customer behavior online and a pricing algorithm based on this model. Using simulations, we characterize the performance of this algorithm and other simple and deployable pricing schemes under different customer behavior and system load profiles. Based on our work, we propose a pricing scheme that combines the best features of the different pricing schemes and analyze its performance.     

液体洗涤剂微机控制配料系统

采用集散控制技术研制了液体洗涤剂生产的微机控制配料系统,文章配合框图介绍其系统组成和功能特点,阐述称重方法及配料原理,并对配料系统运行方式及工艺流程进行说明。     

A heuristic approach to batching and scheduling a single machine to minimize setup costs

In this paper we consider the problem of creating batches of parts, to be processed in a flexible manufacturing cell, and scheduling their operations. We consider the case in which the system consists of one machine and at most k parts may be present in the system at the same time. Given that each part requires a sequence of operations, and each operation requires a given tool, the objective is to minimize the total number of setups. We develop a heuristic algorithm for its solution and we present an extensive computational experience.     

基于大纲的数据流自适应聚集算子的实现

采用基于大纲的数据流自适应聚集算子的批处理（Batching processing）算法处理数据流,Batching算法能够随着流速的变化动态调整自己的执行策略,以便更好地利用有限的系统资源提供尽可能好的查询质量,并且可以在Batching算法的基础上根据不同的流聚集算子提出相应的优化算法,进一步提高查询质量并真正达到或接近实时查询。实验结果已在北大Argus数据流管理系统中得到成功应用。     

数据流系统中一种基于速率的抢占式批处理方法

针对数据流的特征,提出了一种基于速率的抢占式批处理方法。一个查询计划是一个操作符序列。文章将一个查询计划划分为不同的操作单元,并为不同的操作单元分配不同的优先级,而且这个优先级随系统因素的变化而动态改变,根据变化的优先级来动态调度操作单元,采取抢占式调度,从而提高连续查询的查询效率。实验表明该方法不但能提高系统的总体性能,而且可以减少元组的平均等待时间,大大提高了元组的输出速率。     

单台批处理机总加权完成时间最小化的启发式算法

批处理机总加权完成时间最小化问题的复杂性目前还没有确定,因此有必要研究该问题的启发式算法．基于对该问题最优解性质的分析,提出了工件分批的最优性质．分别基于WSPT规则和SPT规则对工件进行总排序,利用工件最优分批性质进行分批,提出了两种启发式算法（简称WSPTS和SPTS）．为了检验算法的性能．将提出的算法与此问题的基准算法和常规算法进行了比较,结果表明,启发式算法WSPTS要优于其他的算法,而SPTS算法的性能最优．