Incrementally maintained network→relational database mapping

An incrementally maintained mapping from a network to a relational database is presented. This mapping may be established either to support the efficient retrieval of data from a network database through a relational interface, or as the first step in a gradual conversion of data and applications from a network to a relational database system. After the mapping has been established, the only data mapped from the network to the relational database are the increments resulting from updates on the network database. The mapping is therefore an efficient alternative to mappings that repeatedly map the results of retrievals through the relational interface from the network database to the relational database. This is in particular the case when the two databases reside on different hosts. Applications on the network database may, under certain restrictions, gradually be moved to the relational database, while the mapping incrementally maintains the relational database for the applications that remain on the network database. A detailed, but generic, account of how to build such a mapping from a network to a relational database is given, including all the algorithms needed and examples of their use.     

A New Approach for the Generation of Circles

Two incremental algorithms for drawing circles using short line segments are proposed in this paper. The proposed algorithms can draw manypoints at one time. They use only addition, subtraction, and shift operations except in the initialization of the algorithm. Using this simplified approach we can greatly increase the speed of drawing circles, relative to other conventional algorithms.     

A link between input-output stability and Lyapunov stability

It is shown that incremental boundedness of an input-output operator ensures global asymptotic stability of any motion. A reciprocal statement is set.     

Mistral-3: Parallel solid modelling

This paper describes the design and implementation of Mistral-3, a parallel solid odeller for distributed-memory multicomputers implementing algorithms for creating, ray tracing and incrementally updating octree-based spatial data structures. The system has been designed to be scalable and portable. Scalability is addressed by distributing the control of task and data management between all available processors and portability's solved by building software for the abstraction of a distributed-memory multicomputer. An object-oriented approach to the design is adopted to help produce a structured system. Results are presented showing Mistral-3 has made good use of up to 128 T800 transputers. It has been ported to transputer-and non-transputer-based multicomputers.     

Water jet forming of steel beverage cans

This paper describes the process of shaping fully formed beer and beverage cans with a rotating high-pressure water jet. This is a special variant of incremental forming and enables much larger strains in the product than would be expected from tensile tests. The paper presents experimental results describing the effect of various machine and material parameters. A possible mechanism that explains the observations is presented.     

基于一步法的轿车门内板可制造性分析

一步法有限元模拟可在产品设计模型的基础上进行成形性分析和缺陷预测,本文描述了一步法的关键技术,并给出了它在轿车后门内板可制造性分析中的应用.     

基于磁带分级存储的文件备份系统设计与实现

随着磁盘价格的不断下降,越来越多的容灾备份系统采用将本地数据经过网络传输到服务器磁盘进行备份,但是大数据时代的来,瞄,导致存储压力越来越大。然而在庞大的数据中,有很大一部分数据活跃率并不高。设计并实现了一种基于磁带分级存储的文件备份与恢复系统,采用索引的方式记录并组织备份文件,实现增量备份;该系统将服务器端拆分为两部分,首先将文件数据备份到服务器磁盘,再根据相关时间保留策略,将活跃率较低的数据归档到脏带中。保证了大数据时代服务器磁盘的高效利用。     

无线随钻测量系统的数据压缩协议研究

在随钻测量系统中,目前采用的主要传输技术是泥浆压力波正负脉冲的方法,该方法所固有的缺点是信号传输速率低,因此,在低信号传输速率下,研究数据的压缩技术,从而提高信号的传输效率具有非常重要的意义。提出采用Huffman技术对数据进行压缩,从而实现随钻测量系统的高效传输。实验证明：压缩比可以满足实际应用需求,具有广泛的应用意义。     

增量式光电旋转编码器及在角减速度测量中的应用

介绍了增量式光电旋转编码器的原理、结构，根据输出信号的特征提高测量精度的四倍频处理方法，在此基础上说明了常用的基于编码器的输出信号的测速原理、方法。最后给出了基于增量式光电旋转编码器进行角减速度测量的系统构成，实际应用精度要求采用的最小二乘拟合法的处理方法。     

某增量式数字阀可靠性分析

数字阀作为液压系统的核心部件,一旦发生故障将导致严重后果。为提升数字阀的可靠性,以增量式数字阀的可靠性为研究对象。根据给出的增量式数字阀机械结构和工作原理建立数字阀的可靠性框图,分析得到故障模式和故障机制;建立数字阀故障树模型,进行故障树分析;对故障发生对机构的影响程度进行致命度分析,得到致命性矩阵图。结果表明:数字阀的阀芯不动、阀芯运行卡停、阀芯运行不精确是数字阀工作过程中常见的3种故障,其中阀芯在运行过程中突然卡停是数字阀的致命度中最严重的故障模式。研究成果可为增量式数字阀的结构设计优化和可靠性分析提供一定参考。