EFFECT OF CATHODIC PROTECTION ON FRACTURE BEHAVIOUR OF LOWALLOY STEELS IN SEAWATER

Fracture behaviour of low-alloy steels AIST4340,HY100,Welten60,AISIA537 and A131 inartificial seawater under static,cyclic loading and at cathodic protection potential has beeninvestigated by using the techniques of fracture mechanics, electrochemistry andelectronfractography.The results reveal that at hydrogen evolution potentials(cathodic pro-tection potential)the critical yield strength required for the occurrance of SCC decreasesfrom 985 at corrosion potential(E_c)to 872 MPa.The effect of cathodic protection on crackpropagation of corrosion fatigue(CF)is not simple,it is closely related to the yield strengthof steels and their SCC behaviour.For the steels with high yield strength,cathodic protectionpromotes(da/dN)_Ⅱ evidently,and reduces △K_(th) value.The(da/dN)-△K curves dis-play a plateau at the third stage of CF for steels with medium or low yield strength.It is men-tioned that the cathodic protection potential for oceaneering constructures should be control-led at top level of the protective range.It seems reasonable that the strength of steel foroceaneeing use might be increased by 200 or 300 MPa.     

PRECIPITATION OF TiC IN METASTABLE β-Ti ALLOY

In order to clarify that the IFP and the “Type 2”α phase are also arising from TiC,ametastable β-Ti alloy was selected for investigation in this work.The results showed that af-ter heating the alloy just below the α+β→β transus temperature and quenching,the TiC lay-er existed at the α/β interface.The morphology of TiC is similar to that of the IFP arisingfrom TiH_2 in the α-β two-phase alloys.The IFP TiC also provided an easy crack path orthe crack initiation sites.The fracture is also identical to that caused by IFP TiH_2.The arceddiffractions(characteristic of “Type 2”α)were found in the selected area diffraction pat-terns of some specimens which had been isothermally aged after solid solution treatment.Theparticles which bring on the arced diffractions may be TiC on the basis of structure and lat-tice parameter analysis,not the so called “Type 2”α phase.     

DETERMINATION OF PrCl_3-NaCl-LiCl PHASE DIAGRAM

PrCl_3-NaCl-LiCl phase diagram has been constructed from the phase diagrams of itssub-binary systems and of six quasi-binary systems measured by DTA technique.It is foundthat this ternary system is composed of five liquidus surfaces,seven second crystallizationlines,two peritectic points and one eutectie point.The temperatures and compositions ofinvariant points are as follows:P_1(416℃,30.3 mol% NaCl,44.2 mol% LiCl,25.5 mol%PrCl_3);P_2(409℃,25.0 mol% NaCl,50.0 mol% LiCl,25.0 mol% PrCl_3);E(404℃,20.0mol% NaCl,55.4 mol% LiCl,24.6 mol% PrCl_3).     

工程专业团队的管理

当今社会商业竞争激烈,讲求灵活和创新。现代企业因应时势需要,通常采取以团队为基础的工作小组的组织形式。工程专业机构主要由趋向自我领导和对自己工作表现严格要求的专业人员组成,因而指挥一控制模式不再是有效的管理工具。对于这些工程专业团队,我们需要发展新的思路对其进行管理,并加以激励。本文首先简述与职能部门结构相比,跨职能团队结构日趋流行的原因,进而阐述这类团队领导的典型职责,并根据最近的深入研究结果和笔者的经验,揭示一个有效的团队所具备的特征,因其对团队领导能否有效发挥职责至关重要。     

THE MECHANISM OF ACCEPTING, DONATING AND EXCHANGING ELECTRONS IN SUPERCONDUCTOR

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基于遗传算法的模糊式电力系统稳定器自寻优设计法

通过对模糊控制器工作原理的深入分析,提出了模糊控制本质上是一种分段定常控制的观点,并以此为基础,提出了模糊式电力系统稳定器的自寻优设计新方法,它将模糊控制器的整个设计过程转化成对一组参数进行寻优的过程,解决了在传统设计过程中存在的规则难于获取和参数值难于确定的问题。为了提高多参数寻优的效率,文中提出了一种群体差异度遗传算法,它可以大幅度地缩小搜索空间,从而极大地减少了参数优化过程中的计算工作量。仿真结果显示,用该方法设计的模糊式电力系统稳定器的性能得到了较大提高。     

An Investigation of Error Sources in Computational Fluid Dynamics Modelling of a Co-current Spray Dryer

The paper is focused on identifying error sources in computational fluid dynamics(CFD) predictions of a spray drying process. Seven groups of drying and atomisation parameters were selected for analysis and 13 simulation trials were performed. The theoretical results were compared with experimental data and sensitivity of the simulation results to the analysed factors was determined. The following parameters affecting the accuracy of CFD spray modelling were found: gas turbulence model, particle dispersion, atomising air, initial parameters of atomisation and heat losses to the environment. A major difference in the errors committed during modelling of spray drying process for fine and coarse sprays was observed.     

双馈感应风力发电机位置观测的实验评估

分析了一种无位置传感器双馈感应风力发电机矢量控制的实现方法,给出了无位置传感器转子位置信号观测的方法,最后采用DSP芯片构造了无位置传感器双馈风力发电机实验系统,对该位置观测方法进行实验评估,测试了无位置传感器双馈感应发电机的动静态运行性能,实验结果表明,该位置观测方式具有良好的动态控制性能.     

综合录井仪防雷系统设计与维护

综合录井仪野外作业遭受雷击的事故时有发生,如何避免综合录井仪遭受雷电袭击已成为作业单位和仪器厂家关注的重点。针对此问题,在分析雷击危害的基础土,以胜利石油管理局地质录井公司在3口井作业过程中发生雷击事故为例,阐述了不同仪器部件发生雷击情况以及直接造成的经济损失,经分析确认在综合录井仪现有防雷设施条件下,引起雷击事故主要是雷电感应所致,进而探讨了综合录井仪的电源、信号电缆以及接地系统的防雷设计方法和防雷器件的选用。2005年4月以来的应用情况表明．将防雷器件安装在综合录井仪的相应设备上,防雷效果非常理想。     

X射线荧光岩屑录井仪器

由光谱分析的一般检测原理入手,介绍X射线荧光岩屑分析仪器的基本原理及仪器构成。分析了波长色散型和能量色散型两类仪器的优缺点,简介了XRF仪器结构、特点、技术指标、检测电路和采集软件功能。针对XRF分析仪器的特殊结构阐述了X射线荧光岩屑分析的实践依据。通过室内测试和现场45口井的验证应用,证实该仪器的检测精度、重复性和稳定性等均达到了设计指标要求,为岩屑录井提供了全新手段,丰富了录井资料,为地层的解释评价创造了有利条件。