Metallurgical Investigation of a Prematurely Failed Concentric Reducer Tube Used in a Hot-Rolling Mill

A concentric reducer tube, which was a part of the top exit roughing hydraulic descaler in a hot strip mill failed prematurely under working pressure. A detailed metallurgical investigation comprising physical examination, optical microscopy, scanning electron microscopy, and electron probe microanalysis was carried out to find out the genesis of the failure. Physical examination revealed cracks located symmetrically around the circumference of the tube that ran along its full length, up to the weld beads at both ends. Optical microscopy of etched samples revealed a banded ferrite-pearlite structure and the existence of forging folds near the change-in-section(160° fillets). Cracks were found to initiate from these forging folds. No structural abnormalities were found in the weld beads and heat-affected zones.     

连铸转炉钢包电力牵引车的研制

论述研制连铸转炉钢包牵引车的目的、意义、方案的选择及设计计算校核,对技术要点作出了明确阐述.     

Hypnosis and clinical pain.

Hypnosis has been demonstrated to reduce analogue pain, and studies on the mechanisms of laboratory pain reduction have provided useful applications to clinical populations. Studies showing central nervous system activity during hypnotic procedures offer preliminary information concerning possible physiological mechanisms of hypnotic analgesia. Randomized controlled studies with clinical populations indicate that hypnosis has a reliable and significant impact on acute procedural pain and chronic pain conditions, Methodological issues of this body of research are discussed, as are methods to better integrate hypnosis into comprehensive pain treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multisensory exploration and object individuation in infancy.

Recent research indicates that by 4.5 months, infants use shape and size information as the basis for individuating objects but that it is not until 11.5 months that they use color information for this purpose. The present experiments investigated the extent to which infants' sensitivity to color information could be increased through select experiences. Five experiments were conducted with 10.5- and 9.5-month-olds. The results revealed that multimodal (visual and tactile), but not unimodal (visual only), exploration of the objects prior to the individuation task increased 10.5-month-olds' sensitivity to color differences. These results suggest that multisensory experience with objects facilitates infants' use of color information when individuating objects. In contrast, 9.5-month-olds did not benefit from the multisensory procedure; possible explanations for this finding are explored. Together, these results reveal how an everyday experience--combined visual and tactile exploration of objects--can promote infants' use of color information as the basis for individuating objects. More broadly, these results shed light on the nature of infants' object representations and the cognitive mechanisms that support infants' changing sensitivity to color differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

管道防腐层的失效及对策

介绍了管道防腐层失效的原因和方式。指出水和氧气是防腐层失效的原因,含水量和含氧量决定腐蚀程度,应采取有效措施对防腐层进行及时检查与修复。     

Lifetime and ageing management of nuclear power plants: A brief overview of some light water reactor component ageing degradation problems and ways of mitigation

The susceptibility and tendency for nuclear power plant (NPP) components to undergo changes in their mechanical and physical properties in the course of the NPP lifetime is generally termed as “ageing”. The light water reactor (LWR) nuclear environment is not a begnign one; it is characterized not only by fast neutrons, which can degrade metallic structures, but also relatively high temperatures of coolant water (around 300°C) which may contain impurities (e.g. sulphate, chloride, peroxides) which can cause corrosion. The hydrodynamical conditions of the coolant in steam generators, for example, can cause thermal fatigue, erosion and corrosion; suspended particulate matter can accelerate erosion processes which can lead to wall thinning and lowering of safety margins. Ageing is, therefore, a very complex mixture of factors concerned with materials, temperatures, times of exposure to environments which vary with time and with respect to chemical composition and flow charactertistics.

The paper describes a few ageing phenomena which can be considered important due to their impact on nuclear safety issues; their influence on economic aspects (availability) of NPP is outlined. Mitigation measures for NPP component ageing problems are given together with recommendations for addressing such issues in NPP now and in the future.     

传感器可靠性技术—传感器可靠性特征量

介绍已知试验数据如何计算可靠性特征量的点估计和区间估计     

电站装备失效分析及其预防

简叙了电站装备失效分析程序、失效原因及其失效机理。大量的各种各样的失效，常常涉及一种或多种的失效机理。在众机理中，主要是：腐蚀失效、环境断裂失效、变形失效和断理解失效。     

Development of damage in a 2D woven C/SiC composite under mechanical loading: I. Mechanical characterization

An investigation has been undertaken to determine the damage mechanisms and the associated mechanical response of a 2D reinforced composite of carbon fibers in an SiC CVI-processed matrix subjected to uniaxial tensile and compressive loadings at room temperature. Under tension loading, an extended non-linear stress/strain response was evidenced and related to a multi-stage development of damage involving transverse matrix microcracking, bundle/matrix and inter-bundle debonding as well as thermal residual stress release. This tensile behavior proved to be damageable-elastic with respect to a fictitious thermalstress-free origin of the stress/strain axis lying in the compression domain. In compression, after an initial stage involving closure of the thermal microcracks present from processing, the composite displayed a linear-elastic behavior until failure. The extent of damage over the material was characterized quantitatively at the microscale by the decrease of the average transverse microcrack spacing and at the macroscale by the decrease of both the longitudinal Young's modulus and the in-plane Poisson's ratio.     

70推土机主离合器分离杆螺栓失效分析

主离合器分离杆螺栓是一个重要安全件，使用中经常发生断裂。经过失效分析确定断裂原因是由其配件引起。提高配件的冷加工质量及改进结构，可解决分离杆螺栓的断裂问题。