期货市场促进“铜冠”牌阴极铜创国际品牌

文章介绍了期货交易所由于其特殊的机制,而对其注册上市产品的质量提高有显著的促进作用,同时介绍了“铜冠”牌阴极铜在LME注册成功,取得进入国际市场通行证中的一些情况。     

基于电力载波通信的远程路灯监控系统设计

设计了一种基于atmega162单片机和电力载波芯片LME2200C的路灯监控系统。采用单片机实时监控路灯的运行情况,并通过电力线进行数据传输,实现了对路灯的远程监控和管理;实际测试结果表明,系统在一定距离内可以取得良好的效果。     

警用无线通信的信道自适应性能研究

当前对于无线信道自适应性能的研究,仅在时不变信道模型下通过分析算法来推导说明,缺乏有效的仿真研究和验证。文中针对警用无线通信特点,并广泛适用于无线通信研究,建立了一种离散时变码间干扰信道模型,通过在部分离散时间点的信道跳变来模拟信道的时变,在此信道模型下研究自适应均衡器基于最小均方误差准则的最小均方和递推最小均方算法,仿真证明：该研究设计的自适应均衡器具有良好的信道自适应性能。     

Chemisorption-facilitated dislocation emission and motion, and induced nucleation of brittle nanocrack

Using a special TEM constant deflection device, the change in dislocation configuration ahead of a loaded crack tip before and after adsorption of Hg atoms and the initiation of liquid metal-induced nanocracks (LMIC) have been observed. The results show that chemisorption of Hg atoms can facilitate dislocation emission, multiplication and motion. Nanocracks will be initiated in the dislocation-free zone (DFZ) or at the crack tip when chemisorption-facilitated dislocation emission, multiplication and motion reach a critical condition. On the basis of the available experimental evidence concerning liquid metal embnttlement (LME), a new mechanism for this phenomenon is considered. This involves the fact that the decrease in surface energy induced by chemisorption of Hg atoms results in a reduction in the critical stress intensity factors for dislocation emission and the resistance for dislocation motion. On the other hand, the plastic work and KIC will decrease with the decrease in the surface energy.     

中国东部沿海四省一市PM2.5浓度遥感估算方法研究

卫星遥感反演的气溶胶光学深度（AOD）产品已被广泛应用于近地面PM_2.5浓度的估算。已有研究表明通过构建AOD和PM_2.5之间的高级统计模型—线性混合效应模型（LME）可以有效获取近地面PM_2.5浓度的空间分布,但由于引入了大量的气象和土地利用等因子,使得模型对变量的解译能力有所降低。为此,基于MODIS AOD（空间分辨率：3 km）,以我国东部长江三角洲—福建—广东（YRD-FJ-GD）为研究区,构建了两种非参数机器学习模型,即支持向量机（SVM）和随机森林（RF）模型,来估算2018年YRD-FJ-GD地区的近地面PM_2.5浓度,并将其与线性混合效应模型（LME）的估算结果进行对比。研究发现,3种模型估算的PM_2.5浓度与地面实测值之间的R²均高于0.6,其中,RF模型的估算精度最优,模型拟合的R²高达0.91,比SVM模型（R²=0.79）和LME模型（R²=0.64）的估算结果分别提高了13%和30%;且RMSE（~9.07 μg/m³）也远低于LME（~19.09 μg/m³）和SVM模型（~17.29 μg/m³）。此外,由随机森林（RF）模型估算的2018年YRD-FJ-GD地区的PM_2.5空间分布显示,长江三角洲（YRD）地区的年均PM_2.5浓度最高（>46 μg/m³）,其次为广东省（GD）,福建地区（FJ）的年均PM_2.5浓度最低（<37 μg/m³）;4个季节的平均PM_2.5浓度则呈现冬季（46.32 μg/m³）>春季（38.80 μg/m³）>秋季（36.15 μg/m³）>夏季（30.16 μg/m³）的分布格局。研究结果表明：与高级统计模型（LME）和机器学习（SVM）相比,随机森林（RF）模型能更好地应用于YRD-FJ-GD地区的PM_2.5浓度估算。     

Effect of oxygen on liquid sodium embrittlement of T91 martensitic steel

The liquid sodium embrittlement susceptibility of the T91 steel in a standard metallurgical state has been studied with varying dissolved oxygen levels. The experimental procedure consists of a pre-exposure wetting step in static sodium before mechanical testing in liquid sodium. The oxygen impurity plays the role of a wetting promoter that facilitates LME of the T91 steel rather than taking part in the fracture process. Brittle grain boundary decohesion is observed using transmission electron microscopy on focused ion beam prepared foils. This settles the issue about the susceptibility of steels to liquid metal embrittlement in liquid sodium.     

Measurements of the interface between 5083 aluminium and liquid mercury using impedance spectroscopy

In natural gas processing plants, the aluminium oxide passive layer has been postulated to protect the underlying aluminium from mercury embrittlement. Under certain circumstances the oxide film may break down, leading to catastrophic failure. In this study, impedance techniques are used to investigate the interface between Al-5083 and liquid mercury at room temperature. The effects of aging time, aging atmosphere and mercury exposure time on the interface were studied and are discussed in terms of the nature of the film. The implications of this work on the integrity of aluminium gas processing equipment exposed to mercury are examined.     

Temperature effect in the maximum propagation rate of a liquid metal filled crack: The T91 martensitic steel/Lead–Bismuth Eutectic system

The liquid metal embrittlement sensitivity of a modified 9Cr1Mo martensitic steel in contact with Lead–Bismuth Eutectic was studied as a function of the temperature in a wide range of deformation rate. A fracture mechanics approach (crack tip opening displacement and J-Δa) combined to a fractographic study was applied to study the maximum brittle crack propagation rate. Comparison of these data with the temperature evolution expected from the stress assisted dissolution model discards this model as the embrittlement mechanism. Thermally activated ductility recovery mechanisms fail to account for the experimental results. However, the data is compatible with a physi-sorption rate limiting process. The adsorption energy extracted from the temperature evolution of the maximum crack propagation rate compares favourably with existing Ab-Initio calculations. This strongly suggests that the LME mechanism is linked with the direct effect of surface adsorption.     

局部特征尺度分解结合局部均值解调的齿轮故障诊断

为了准确地进行故障诊断,根据齿轮故障振动信号的多分量调幅-调频特征,提出了一种新的解调方法--局部均值解调法,将之与局部特征尺度分解相结合进行齿轮故障诊断。该诊断方法首先对齿轮振动信号运用局部特征尺度分解,得到若干个内禀尺度分量,然后应用局部均值解调法求取每个分量的调频分量,最后根据瞬时频率的频谱进行故障诊断。采用仿真信号将局部均值解调法与Hilbert解调法、经验调幅调频分解法进行了对比,结果表明,局部均值解调法的精确性更好。通过齿轮故障振动数据的分析,验证了局部特征尺度分解结合局部均值解调的故障诊断方法的有效性。     

基于电源线载波通信的电子拣货标签

为了改变传统串行通信需要单独的数据通信线而引起的布线问题,开发了低压交流电源线载波通信模块,并成功嵌入物流自动化领域的电子拣货标签。标签基于PIC单片机控制,并结合段码管控制电路,实现拣货。载波通信模块采用新型的电力线载波调制解调芯片,并结合外围模拟滤波电路,实现电源线信号的调制解调。单片机与载波通信模块采用3线串行口连接。可以根据拣货的实际需要,增加或删改硬件,配置各种类型的电子标签。标签整体造价低廉,实际应用表明,数据通信安全、可靠。