Microstructures and wear resistance of large WC particles reinforced surface metal matrix composites produced by plasma melt injection

Large WC particles (− 840 μm-+ 420 μm) reinforced surface metal matrix composites (SMMCs) were produced using plasma melt injection (PMI) process on a Q235 (similar to ASTM A570 Gr. A) low carbon steel substrate. Microstructures of the SMMC were observed using scanning electron microscope (SEM), and the composition was determined with energy dispersion spectroscopy (EDS). Phases were analyzed with X-ray diffraction. Micro-hardness of the SMMC was tested. Wear losses of the SMMC layer were evaluated under dry friction conditions and compared with those of the substrate material. The results show that the large WC particles are caught by crystallized metal and stay in the upper part of the SMMC layer, and there is only a little melting on the outer surface. No sinking down of WC particles occurs. The SMMC layer is well bonded to the substrate, and the interface is crack free. The wear resistance of the Q235 substrate is greatly improved with large WC particles injected.     

用于圆筒状零件内表面等离子体浸没离子注入的偏转电场法

等离子体浸没离子注入（ＰＩＩＩ）为解决束线离了注入所难以解决的圆筒状零件内表面注入处理问题提供了新要可能途径，但在应用中却受到注入能量和注入剂量偏代的限制，本文针对这一问题了偏转电场法用以提高内表面注入的能量和注入剂量，实验结果表明，采用这一方法可以有效地改善圆筒状零件内表面注入的注入情况，注论述工提高了２５％～１００％，注入剂量提高了７３％～１１３％，注入脉冲宽度的延有利于注入离子向部深入，利于     

纳米SnO2和SnO2／SiO2材料的正电子湮没研究

采用溶胶一凝胶法制备了纯纳米ＳｎＯ２和掺杂ＳｉＯ２的纳米ＳｎＯ２材料，应用Ｘ射线衍射和正电子湮没寿命谱等手段进行了纳米材料的界面结构和纳米晶粒的生长过程，结果表明，所制备的纳米ＳｎＯ２和ＳｎＯ２／ＳｉＯ２材料中只存在两类缺陷，分别对短寿命τ１和中等寿命τ２，材料中两类缺陷的数量比与粒径有关，纳米ＳｎＯ２晶粒生长随热处理温度升高为分两个阶段，低于晶化临界温度时，晶粒生长缓慢，高于此温度时，则生长迅速     

螺纹钢筋负偏差轧制技术应用实践

结合承钢生产实际，主要叙述螺方钢筋负偏差轧制中的经验、效果及存在的问题。     

小方坯连铸中间包用耐火材料

讨论了小方坯连铸中间包用耐火材料的部分品种及性能要求，为小方坯连铸中间包用耐火材料的选择提供了参考。     

温度传感器陶瓷热敏元件包封的设计与响应时间的研究

陶瓷热敏元件可视不同的使用环境选择单层或复合包封。根据传热学理论，建立了包封系统瞬态导热方程，并在简化假设条件下得到了热响应时间的解析解，分析了响应时间的取决因素，依据包封材料的热物性计算出几种包封方案响应时间的理论值。通过实验，对几种包封系统热响应时间进行了测量。其结果与理论值接近，表明该理论可用于指导最佳包封方案的设计。     

Nondestructive measurement of soluble solid content of navel orange fruit by visible-NIR spectrometric technique with PLSR and PCA-BPNN

A relationship was established between the soluble solid content (SSC) of navel orange fruit determined by destructive measurement and visible-near infrared diffuse reflectance spectra in the wavelength range of 350-1800 nm. Multiplicative scatter correction (MSC) and standard normal variate correction (SNV) were applied to the spectra, partial least squares regression (PLSR) and back propagation neural network (BPNN) based on principal component analysis (PCA) were used to develop the models for predicting the SSC of intact navel orange fruit. Thirty-eight unknown samples were used to evaluate the performance of these models. The principal component analysis-back propagation (PCA-BPNN) method with MSC spectral pretreatment obtain the best predictive results, resulting in correlation coefficient, root mean square error of prediction (RMSEP), average difference between predicted and measured values (Bias) of 0.90, 0.68 °Brix and 0.16 °Brix, respectively. Experimental results indicate that PCA-BPNN is a suitable tool to model the non-linear complex system, with additional advantages over PLSR, and the vis/NIR spectrometric technique can be used for measuring the SSC of intact navel orange fruit, nondestructively.     

除氧头接管座焊缝开裂分析及修复

某电厂4号、5号机组除氧器除氧头的三级抽汽平衡汽管(简称三抽管道)的接管座焊缝多次发生开裂泄漏,并且除氧头筒体内壁也存在大量裂纹。分析认为,造成焊缝开裂和除氧头筒体内壁裂纹的主要原因是接管座角焊缝未焊透及除氧头淋水盘结构不合理。对此,提出了修复改进措施。     

无线传感器网络移动节点自装配方法研究

移动传感网络系统的自装配功能实现了对系统形态上的控制,提高了系统对环境的适应能力。本文设计并实现了一套可自装配的移动传感器网络系统,并且提出了一种系统自装配的方法。无线传感器网络中的一个移动节点可以自主移动到另一移动节点的装配面附近,在误差范围内,通过红外测量与电子罗盘的引导实现两个节点之间的自装配。实验结果表明该系统与方案可行。     

基于神经网络模型的在线电压稳定裕度评估

为了在线快速评估当前电力系统稳定裕度,将回归分析和人工神经网络模型同时应用于电压稳定评估,用回归分析法来求负荷对电压稳定裕度的灵敏度,此种方法克服了传统潮流方法求取灵敏度的缺陷。为了改善神经网络模型的性能,根据预先设置好的灵敏度阀值来进行特征选择,从而减少输入变量的维数;然后设计了一个三层BP神经网络进行训练,求取电压稳定裕度,取得了很好的预测效果,最后在IEEE30节点系统上进行了验证。证明此方法的有效性。