Laboratory investigation of reinforcement corrosion initiation and chloride threshold content for self-compacting concrete

Time-to-corrosion (T_i) of reinforcement in concrete and chloride threshold content (C_th) are important service life determinants for reinforced concrete structures in chloride-laden environments. In this study, the two determinants of a series of self-compacting concretes (SCC) and regular concretes were experimentally investigated. A new sampling approach for C_th determination (milling powder from corrosion active site at the rebar/concrete interface) was adopted to accurately express chloride content resulting in corrosion occurrence. It is found that the T_i and C_th follow the 3-parameter Weibull distribution. The results indicate that the corrosion initiation of rebar in concrete slabs depends upon both cement alkalinity and superplasticizer. Rebar, embedded in high alkalinity cement SCC, exhibits better corrosion resistance as indicated by the longer T_i, higher C_th and larger Weibull modulus, m. A larger Weibull modulus indicates that anti-corrosion performance of rebar in slabs is more stable and less scattered. The effects of specific superplasticizer on rebar corrosion resistance are discussed from the viewpoint of air void amount and size distribution at the rebar/concrete interface.     

矿井移动机器人运动控制系统研究

介绍了一种可在矿井等未知环境下自主工作的移动机器人运动控制系统设计.该控制系统采用32位单片机S3C2410ARM作为处理器,利用直流电机作为驱动装置.当机器人遇到周围障碍物的情况下能快速、自主地调节行驶速度和行驶方向,该系统具有动态性能好、启动速度快、运行稳定性强等特点.     

基于对话框编写实现坐标方位角正算与反算的程序

通过Visualc＋＋6．0来设计坐标正反算的程序,基于对话框来编写,特别是在控制网平差计算中,用来坐标方位角的推算和平面坐标的正反算,在导线测量中,通过坐标的正反算来确保控制网的精度。该程序可以广泛应用于施工放样等相关工作中,并且用实际的测量工作验证了其准确性和实用性。     

Corrosion of aluminium in the aqueous chemical environment of a loss-of-coolant accident at a nuclear power plant

Aluminium corrosion is a significant concern in the aqueous chemical environment of the reactor containment building following a hypothetical loss-of-coolant accident (LOCA) at a nuclear power plant. Aluminium corrosion may lead to the formation of precipitates that can, in combination with insulation debris, block the recirculation sump screens. This study investigated aluminium corrosion experimentally at both bench and pilot scale under conditions representative of several types of nuclear power plants. Evidence of corrosion was determined using aqueous concentrations measured with inductively-coupled plasma (ICP) spectrometry and surface examinations using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectrometry (XPS), X-ray fluorescence (XRF), and X-ray diffraction (XRD). Corrosion proceeded slowly at pH near 7, but more rapidly at higher pH when the representative pipe insulation material was fibreglass. However, when calcium silicate pipe insulation was introduced into the system, corrosion became insignificant even at pH values near 10. Experimental evidence indicates that the calcium silicate insulation released a significant amount of silicate to the solution. Silicate formed a passivation layer composed of Al₂OSiO₄ with a thickness of more than 10 nm, and this layer effectively inhibited corrosion.     

热处理对原位烧结(Ti,V)C钢结硬质合金组织及耐磨性的影响

利用粉末冶金技术,原位烧结合成了(Ti,V)C钢结硬质合金,并用扫描电镜、X射线衍射仪等研究了热处理对原位烧结(Ti,V)C钢结硬质合金组织和耐磨性的影响。结果表明:烧结态(Ti,V)C钢结硬质合金基体组织为细珠光体组织;1 000℃淬火后的组织转变为片状马氏体+(Ti,V)C硬质相颗粒+少量未溶碳化物;回火过程中合金具有较高的抗回火稳定性,在500℃左右回火时存在二次硬化现象;该合金在1 000℃淬火、经250,500℃回火后具有较好的耐磨性。     

U-Boot的启动分析及基于S3C44B0的移植

U-Boot作为一种通用的BootLoader,可以方便地移植到其他硬件平台上。简单介绍了BootLoader和U-Boot,通过对U-Boot的启动过程以及源代码目录分析,最后完成了基于S3C44B0的移植。     

基于USB2．0的运动控制系统研究与开发

结合运动控制系统的典型功能,开发了基于USB2.0的运动控制系统,根据USB通信的特点提出了一种应用于数控系统的通信方法,并对USB通信的软件设计作了详细的说明.系统采用了带有USB设备控制器的C8051F320单片机,具有丰富的内部资源,可以很好地满足实际需要.     

FANUC Oi C系列CNC数控机床返回参考点故障处理

数控机床在开机之前,通常都要执行回机床参考点的操作,归根于机床断电后,就失去了对各坐标位置的记忆,其回机床参考点的目的在于让坐标轴回到机床一固定点上,即机床的零点,也叫机床参考点(MRP)。回参考点操作是数控机床的重要功能之一,该功能是否正常,将直接影响零件的加工质量。     

HTR-PM中~(14)C产生与释放行为研究

~(14)C具有较长的半衰期,可与稳定同位素一起进入生物圈,从而在核电站的环境影响评价中受到关注.本文基于HTR-PM给出了产生~(14)C的各反应模型,并代以HTR-PM参数,对HTR-PM中~(14)C的年产生量和气态释放量作出估算.最后,将计算结果与CANDU堆型进行了比较.     

基于小波包分析的数据VV＆C方法研究

将小波包分析的特点和优势应用到数据校核、验证和确认中,提出了基于小波包的数据VV＆C验证方法.通过对仿真数据和实测数据的定性和定量对比,证明了小波包分析在数据VV＆C验证方面的可行性.