基于CAN总线驱动器PCA82C250的多主结构分布式工业测控系统的应用研究

本文给出一种全新的、基于CAN总线驱动器PCA82C250的分布式工业测控系统的网络组成。该系统克服了RS-485的许多缺点,既具有CAN总线传输距离远、传输速率快、可靠性高等的特点,又具有等同于RS-232的编程容易、接口简单的优势,可以使工程师完全摆脱对CAN控制器82C200（或者SJ1000）的接口和编程。实际应用表明,这是一种可以替代RS-485,组成简易、实用的CANBUS系统。     

鄂尔多斯盆地陇东地区三叠系延长组浅水三角洲砂体特征及厚层砂体成因

基于47 口井取心资料及130 口井测井资料,综合分析鄂尔多斯盆地陇东地区三叠系延长组长82亚段浅水三角洲主要砂体类型,明确累计厚度大于20m的厚层砂体分布特征,并划分厚层砂体成因类型.根据研究区厚层砂体的形态和发育位置可将其分为两类:第一类厚层砂体呈"宽条带状"分布于平均高水位线及平均低水位线之间;第二类厚层砂体沿平...     

SWRH82B线材拉拔断丝的分析和解决

SWRH82B线材在拉拔时由于拉拔工艺参数不当出现断丝。钢丝中心出现断裂时,通过改变道次压缩率和拉丝模工作锥角,使其合理匹配来解决,保证工作区角度为14°时,压缩率大于20%;工作区角度为12°时,压缩率大于18.5%。当出现钢丝表面横裂时,通过控制拉丝模工作区长度解决,根据钢丝拉拔前后直径和拉丝模工作锥角,计算出工作区最小长度,保证工作区实际长度是最小长度的2倍以上。     

Finite element simulation of welding residual stresses in martensitic steel pipes

Abstract

Finite element (FE) simulations of the welding of two high grade steel pipes are described. The first is a P91 steel pipe welded with a similar P91 weld consumable, and the second is a P92 steel pipe welded with dissimilar nickel–chromium based weld consumables. Both welds are multipass circumferential butt welds, having 73 weld beads in the P91 pipe and 36 beads in the P92 pipe. Since the pipes and welds are symmetric around their axes, the FE simulations are axisymmetric, allowing high FE mesh refinement and residual stress prediction accuracy. The FE simulations of the welding of the P91 and P92 pipes comprise thermal and sequentially coupled structural analyses. The thermal analyses model the heat evolution produced by the welding arc, determining the temperature history throughout the FE models. Structural analyses use the computed temperature history as input data to predict the residual stress fields throughout the models. Post-weld heat treatment (PWHT) of both pipes has also been numerically simulated by assuming that the FE models obey the Norton creep law during the hold time period at 760°C. The residual stresses presented here have all been validated by corresponding experimental measurements. Before PWHT, it has been found that, at certain locations in the weld region and heat affected zone (HAZ) in the pipes, tensile hoop and axial residual stresses approach the tensile strength of the material, presenting a high risk of failure. It has also been found that PWHT substantially reduces the magnitude of residual stresses by varying degrees depending on the material.     

南方“工程之星3.0”数据采集方法

RTK是能够在野外实时得到厘米级定位精度的测量方法,它采用了载波相位动态实时差分方法,它的出现在工程放样、地形测图,各种控制测量等测量工作中,极大地提高了外业作业效率。根据笔者多年测量经验,地形测图方面采用的方法:运用实时动态(RTK)测量技术,结合南方数码公司"工程之星3.0"软件,采用清华三维编码、简码方式采集野外数据,用VB小程序进行数据格式转换,在"南方CASS7.0成图系统"软件,展现数字化地形图。     

机械球磨与HDDR结合制备纳米晶Nd12Fe82B6合金粉末及其组织特征

在氢气氛中机械球磨铸态Nd12Fe82B6(at%)合金,利用机械力驱动使之发生歧化反应,随后进行真空脱氢-再结合处理,获得纳米晶合金粉末材料.采用差示扫描量热法(DSC),分析了歧化态合金粉末的脱氢-再结合行为.利用X射线衍射(XRD),扫描电镜(SEM),及透射电镜(TEM)等测试方法,研究了球磨及脱氢-再结合过程中合金粉末的相变与微观组织.结果表明:在0.2 MPa氢气氛中球磨20 h,可使Nd12Fe82B6合金完全歧化,形成晶粒尺寸约为8 nm的Nd2H5,Fe2B和α-Fe的纳米歧化组织,并且粉末颗粒细化到0.5μm～1.0 μm.在760℃,30 min的条件下进行真空脱氢-再结合处理,获得了平均晶粒尺寸约为30 nm的Nd2Fe14B/α-Fe纳米复相Nd12Fe82B6合金粉末.     

Design of photonic crystal fibers with anomalous dispersion

Photonic crystal fibers (PCFs) have attracted greatattentionin recent years due to their interesting proper-ties ,such as endless single-mode operation,unique dis-persion and nonlinear characteristics[1 ,2].It has been re-ported that PCFs offer a wide range of potential applica-tions ,such as 2Rregenerators ,optical parametric ampli-fiers ,dispersioncompensationandsuper-continuumgen-eration[3].Also called holey fibers or microstructure fi-bers ,PCFs are optical fibers possessing periodic a…     

SMT在大规模生产中的应用

以松下ＨＤ８２录象机单板的大规模生产过程为范例，分析探讨了ＳＭＴ工艺在大规模生产中应该注意的几个问题和工艺要点，并提出了解决方法和应对措施。对ＳＭＴ技术实际生产中的应用有一定的参考价值。     

Transporting TEX into the HITAC VOS3 environment

An attempt to transport T_EX82 and to implement a typesetting program which realizes the output of the former at Hokkaido University Computing Center is described. The target operating environment and the environment required for running the T_EX82 program are compared. The transporting procedure and the requirements for compiling and running the T_EX82 program are described, along with the problems that they caused. The measures taken to adapt T_EX82 to the target operating environment are explained, where considerations of how the system-dependent parts are designed in accordance with the conventions of the target environment are illustrated in detail. The working principles and some implementation details of the output typesetting program are described, where rather esoteric techniques are employed. Finally, some measurements of performance are given.     

SWRH82B高碳盘条脆断原因分析

分析了SWRH82B盘条脆断问题，结果表明，尖状断口试祥的中心处存在着较严重的碳偏析，导致了组织转变上的差异，从而使拉拔变形不均匀。通过在冶炼上配备末端电磁搅拌装置，使钢坯的碳偏析指数小于1．04，可明显减少脆断现象和尖状断口发生率。