镀锌钢板的CO2激光焊焊接性

以裁焊板工业生产为背景，对汽车用镀锌钢板的CO2激光切割板坯的CO2激光焊焊接性进行了试验研究。对于不等厚和等厚的镀锌板拼接进行CO2激光焊接，在激光功率4000W时其焊接速度可达0．1m／s。对镀锌钢板激光切口拼接的激光焊接与铣口拼接的激光焊接的焊缝形貌和硬度进行了比较，它们产生的焊缝宽度在0．5-1．0mm范围，激光焊缝最大硬度比母材硬度高出1-1．5倍，激光焊接对激光切口拼接与铣口拼接两者都可获得等同的宏观焊接质量。     

基于特征选择和改进K-均值聚类的异常用电行为检测算法

窃电等异常用电行为严重影响着电网系统的安全、可靠和稳定运行,传统异常用电检测方法存在模型复杂、准确率低等问题。提出了一种基于特征选择和改进K-均值聚类的异常用电检测算法,首先从用电量变化、线路损耗和电力参数三个维度提取15维特征构成特征向量,然后利用相关向量机(Relevance Vector Machine, RVM)进行特征选择,自动确定最优特征集合,最后提出一种基于信息增益的改进K-均值聚类算法对最优特征集合进行聚类分析,从而实现异常用电检测。基于爱尔兰智能电表公开数据集开展实验,结果表明,所提方法在精准率、召回率和ROC曲线AUC值三项指标方面均能获得良好的表现性能,明显优于传统方法。     

Synthesis, Characterization and Gas Sensing Properties of In（OH）3 and In2O3 Nanorods through Carbon Spheres Template Method

Poly-crystalline In(OH) 3 nanorods have been successfully prepared via a urea-based precipitation using the colloidal carbon spheres as the templates. After calcinations, the resulted In 2 O 3 nanorods with poly-crystalline structure were fabricated. Structure and morphology of the product were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The possible formation process was schemed. The sensor gas properties towards C 2 H 5 OH and CO were examined.     

高氯酸铵脱除介孔氧化硅有机模板剂

采用AP-HNO₃组成的体系在低温(100 ℃左右)下快速完全地分解介孔氧化硅材料(SBA-15)的模板剂,得到开放孔道的SBA-15(N-SBA-15)。透射电镜(TEM)照片显示,N-SBA-15具有高度有序的二维六方结构(p6mm)。与焙烧产物(C-SBA-15)的孔容(1.03 cm³·g-1)和孔径(6.5 nm)相比,N-SBA-15具有较大的孔容(1.40 cm³·g-1)和孔径(10.4 nm)。小角XRD谱图表明N-SBA-15没有明显的骨架收缩,红外光谱(FT-IR)显示其孔道表面存在大量硅羟基。与C-SBA-15相比,N-SBA-15只有很少的微孔孔容。因此,AP氧化是一种条件温和的获取高质量多孔氧化硅阵列材料的有效手段,它也适用于多种具有不同对称性介孔氧化硅(如Fm3m,Im3m,Ia3d等结构)模板剂的脱除。      

CO2激光焊接600 MPa DP钢接头组织与性能

采用CO2激光对抗拉强度为600MPa,厚度1.4mm的DP钢进行焊接.研究焊接速度对焊缝外观和截面成形的影响、接头的组织特点、硬度、强度和成形能力.结果表明,激光功率相同,焊接速度较低时焊缝易产生气孔,焊接速度较高时易发生飞溅;焊接速度对焊缝熔深及熔宽也有影响.焊缝区组织主要由马氏体构成,从焊缝、焊接热影响区到母材,组织中马氏体含量下降,接头的最高硬度出现在焊缝或热影响区.在平行于焊缝方向,焊接接头的抗拉强度高于母材,垂直于焊缝方向,接头的抗拉强度与母材相当.由于焊缝出现马氏体组织,接头的塑性和韧性降低,板材的冲压成形能力下降.     

A theoretical and experimental investigation of the tool-tip vibration and its influence upon surface generation in single-point diamond turning

This paper presents a theoretical and experimental investigation of the influence of tool-tip vibration on surface generation in single point diamond turning (SPDT). Although it is well known that the relative vibration between the tool and the workpiece plays an important role in the surface generation in single-point diamond turning, most of the prior work has been focused on studying the relative tool-work vibration in the infeed (thrust force) direction while the significant contribution of the effect of the tool-tip vibration in the cutting force direction has been overlooked. In the present study, two characteristic peaks (twin peaks) are identified and found to be corresponding to the tool-tip vibrations by power spectrum density (PSD) analyses. The vibrations possess the features of small amplitude but high frequency. A physical model is proposed to capture the dominant factor based on the characteristic and it reveals that the twin peaks are attributed by the impact between the tool tip and workpiece and the process damping effect. Hence, a geometric model of surface roughness is proposed to take account of tool-tip vibration and it is verified through a series of experiments. The simulation results have been found to agree well with the experimental results.     

烟火药自动混药生产线技术特点分析及质量监督

为进一步了解烟火药自动混药生产线的技术特点,实现对烟火药自动混药生产线进行准确的质量监督,结合烟火药的性能原理和日常质量监督工作,介绍自动混药生产线的总体概况、生产线各重要单机设备的功能和结构,重点探讨烟火药混药自动生产线的技术特点,并提出在质量监督工作中应注意的问题,为适应“软检测”要求奠定了一定的理论基础。     

Combustion synthesis of CaB6 powder from calcium hexaborate and Mg

As one of the important metal-borides, calcium hexaboride (CaB₆) is applied in refractory materials, metal deoxidant, neutron absorbent, wear-resisting agent and functional ceramic materials. Generally, CaB₆ is produced from B₄C or B₂O₃ which is obtained at high temperature and high cost. In this study, the CaB₆ powder was prepared through combustion synthesis by using calcium hexaborate and magnesium as starting materials. The calculated adiabatic temperature of CaB₆O₁₀–Mg system reached 2406.69 K. The XRD analyses of combustion products showed that there existed a small amount of Mg₃B₂O₆ and Ca₃(BO₃)₂ besides CaB₆ and MgO. The XRD patterns of products leached by HCl indicated the major part of the leached sample is comprised by CaB₆, showing that MgO and by-products were efficiently leached out. In addition, the technological conditions for combustion synthesis were investigated. It is resulted that larger particle size of CaB₆O₁₀ and higher compacting pressure is beneficial to the production of CaB₆.     

海洋环境中微生物腐蚀及其防护研究进展

微生物腐蚀是当前我国海洋工程设施发展亟待解决的问题。综述了近几年来海洋环境中微生物腐蚀的研究方法及其防控措施,重点对液中高压脉冲电场杀菌技术做了详细的概括和分析。     

水热合成BiVO4催化剂及其可见光催化活性

以Bi(NO3)3.5H2O和NH4VO3为原料,用水热法合成新型的可见光催化剂BiVO4,以活性蓝M-2GE染料废水为目标污染物,通过XRD、TEM和UV-vis DRS等表征手段考察了水热合成时间、水热温度和前驱物pH对催化剂可见光活性和晶型的影响,结果表明,在160℃、pH=7.01和水热合成时间2 h条件下合成的催化剂光催化效果最好,光照210 min,对M-2GE的去除率达98%。其吸收边带为520 nm,能隙禁带宽约2.4 eV。