Magnetic field detection for current evaluation by magnetic force microscopy

A current measurement method through magnetic field detection by magnetic force microscopy was proposed and demonstrated. We observed the magnetic field induced by an AC below 2.2 μA around a GaAs/AlGaAs mesa stripe. To achieve high sensitivity in magnetic field detection, we tuned the AC bias frequency to the torsional resonant frequency of the cantilever. As a result, the sensitivity of the magnetic field detection was much improved and specific features of the magnetic field around the mesa stripe were clearly observed at a current in sub-μA range.     

布喇格光栅在温度测量中的应用

文中阐述布喇格光栅测温的新应用。将金属的热膨效应和布喇格光栅的弹光效应结合起来应用,提高布喇格光栅测温的灵敏度和测量范围。设计出实用传感器的给出实验图表。     

采用单臂电桥实现高精度温度检测的软件补偿技术

单臂电桥测温电路结构简单,但存在误差而难以实现高精度温度检测。文中介绍一种新的、能从根本上消误差的软件补偿方法,具有实现成本低、测温精度高、易于实现等优点,已在实际工程中取得良好推广应用。     

点型红外可燃气体探测技术

介绍一种较新的可燃气体探测技术——点型红外可燃气体探测技术,概述了其工作原理(基于气体的光谱本征吸收原理,利用可燃气体吸收特定波段的红外光,通过传感器件接收红外光光通量的物理变化来实现对可燃气体的探测),分析了探测器具体构成(由气体检测单元和信号处理电路单元两部分组成),并给出具体硬件(电源电路、信号放大电路、输出接口电路)设计思路和软件标定算法。     

外电场作用下混凝土中离子的迁移与分布规律研究

以饱和石灰水为电解液,对外掺3％NaCl的混凝土圆柱体试件进行电化学除氯试验,研究了三种不同电流密度( 1.0 A/m2、2.0 A/m2、3.0 A/m2)作用28d后混凝土中氯离子和钾、钠离子的分布规律.结果表明:电流密度越高时,在距离钢筋越近区域,混凝土中的残余氯离子含量越少;电流密度为2.0 A/m2和3.0A/m2时,可使混凝土中距离钢筋20mm范围内的氯离子含量均降低到水泥用量0.15％(占水泥质量)以下.在电化学除氯电场作用下,大量钾、钠离子向钢筋附近区域迁移和聚集,使混凝土试件内层钠离子含量达到最外层的4.8～17.3倍,钾离子含量达到最外层的3.8～17.5倍,从而增加了混凝土内部发生碱骨科反应破坏的风险,并导致部分水化产物分解,使混凝土与钢筋粘结力显著降低.     

Effects of temperature and current density on the surface hardness and tribological properties of Ti-6Al-4V alloy by molten salt carburization

Surface hardening of Ti-6Al-4V alloy was achieved by carburization in a molten salt bath containing BaCO₃ as the carbon-yielding agent with electrolysis within the temperature range 790–930°C. The hardness of the total carburizing layer (TCD) is influenced by the bath temperature, the applied current density and the carburizing period. The major hardening effect is considered to be the formation of a solid solution of carbon in -Ti. The oxide film wrapping at the outermost surface of cathodically charged specimens, identified to be mainly BaTiO₃, was formed irrespective of the bath temperature during the quenching process and has no effect on the surface hardening. The optimal carburizing parameters obtained in this study for surface hardening are carburizing at 930±10°C (bath temperature) and 0.3 A/Cm² (applied current density) for 90 min (carburizing period), while those for tribological properties improvement are carburizing at 860±5°C and 0.3 A/Cm² for 90 min.     

建筑业信息化标准体系设计

建筑业信息化标准是规范建筑行业信息化工作的强有力保障。为了完善我国建筑业信息化标准系统性,阐述了信息化标准体系设计原则, 建立了两种信息化标准体系结构模型, 明确了两种结构模型各层次标准的对应关系, 总结了信息化标准体系编制情况, 为指导建筑业信息化标准化建设提供依据。     

Applying fluorescence based technology to the recovery and isolation of Cryptosporidium and Giardia from industrial wastewater streams

As increasing water shortages continue, water re-use is posing new challenges with treated wastewater becoming a significant source of non-potable water. Rapid detection strategies that target waterborne pathogens of concern to industry are gaining importance in the assessment of water quality. This study reports on the ability to recover spiked Cryptosporidium and Giardia from a variety of industrial wastewater streams of varied water quality. Incorporation of an internal quality control used commonly in finished water-enabled quantitative assessments of pathogen loads and we describe successful analysis of pre- and part-treated wastewater samples from four industrial sites. The method used combined calcium carbonate flocculation followed by flow cytometry and epifluorescence microscopy. Our focus will now aim at characterising the ambient parasites isolated from industrial wastewater with the objective of developing a suite of highly specific platform detection technologies targeted to industrial needs.     

温度和电流密度对AZ63镁合金牺牲阳极在淡水中电化学行为的影响

用恒电流阳极放电和腐蚀形貌金相观察,考究了在淡水中温度２０￣８０℃、电流密度０．０１５￣１．２０ｍＡ／ｃｍ＾２的范围内,不同工作温度和电流密度下ＡＺ６３镁基合金牺牲阳极的电化学行为。结果表明：在淡水中,工作温度上升对ＡＺ６３镁阳极的电流效率和腐蚀形貌影响不大,工作电位略有负移;随阳极极化电流密度的增大,ＡＺ６３镁阳极的电流效率变化不大,工作电位正移明显,腐蚀形貌变得更加凹凸不平。在上述试验条件下没     

Detection and diagnosis for multiple faults in VAV systems

Detection and diagnosis of multiple faults in variable air volume (VAV) systems using principal component analysis (PCA) and joint angle analysis (JAA) are presented. Multi-level principal component analysis models including system- and local-level are built to detect the multiple faults occurred in VAV systems simultaneously. As the initial detection, system-level principal component analysis model is used to discover the abnormities in view of the whole systems. And two local-level principal component analysis models are used to further confirm the occurrence of the faults. With the multiple faults separated into different locations, joint angle analysis is used to isolate the faults one by one according to corresponding local models.