氧化锆陶瓷表面Ag-TiO_2抗菌薄膜的制备及性能

采用Sol-Gel法制备5%(原子分数)银掺杂二氧化钛溶胶,并采用浸渍提拉法将其涂覆于氧化锆表面。利用X射线衍射(XRD)、扫描电镜(SEM)等研究手段测试薄膜性能,采用抑菌圈实验和MTT实验评价其抗菌性和细胞毒性。结果表明:采用浸渍提拉法可在氧化锆表面制备一层均匀的Ag-TiO2薄膜,薄膜表面可见散在分布的Ag颗粒;经500℃煅烧后为锐钛矿TiO2,Ag掺杂可抑制TiO2晶粒的生长,并增加了TiO2薄膜的光催化活性;该薄膜在无光照条件下具有良好的抗菌性能,抑菌距离达到4.5mm左右;细胞毒性为Ⅰ级,符合口腔生物材料的应用标准。     

副产物硫酸铵辅助制备氧化镁纳米棒

为了寻找规模化合成氧化镁纳米棒的新方法,通过氨水沉淀硫酸镁制备了花状氢氧化镁前驱体,探索了前驱体热分解过程中副产物硫酸铵的存在和煅烧温度对产物物相和形貌的影响。结果表明:表面吸附硫酸铵的花状氢氧化镁800℃煅烧2 h再洗涤,可以得到长度1~2μm、直径30~100 nm的氧化镁纳米棒;沉淀产物花状氢氧化镁经洗涤后再在600~800℃煅烧2 h,可以获得平均直径2μm的氧化镁纳米花;副产物硫酸铵对氧化镁纳米棒形成起了结构导向的作用。     

Fabrication and ultraviolet-shielding properties of silica-coated titania-doped ceria nanoparticles

A series of well-dispersed titania-doped ceria nanoparticles Ce1-xTixO2 were rapidly prepared by a novel salt-assisted solution combustion process using correspondent metal nitrates as oxidizers and ethyl glycol as fuel, and then coated with amorphous silica by seeded polymerization using tetraethyl orthoslicate (TEOS). The as-prepared samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and ultraviolet-visible light (UV-Vis) diffuse reflectance spectroscopy. The results indicated that compared with the as-prepared pure ceria nanoparticles, the red-shift phenomenon occurred for Ti-doped ceria nanoparticles with Ti incorporation. Meanwhile, the absorption intensity in the UV light region slightly decreased and transmission rate in visible light region was somewhat enhanced. In comparison with the silica-coated CeO2 nanopowders, the silica-coated Ce0.95Ti0.05O2 nanopowders displayed the same absorption intensity in the UV light region, broader UV absorption band and higher transmission rate in visible light region.     

基于奇异值分解和多级支持向量机的配电网故障类型识别

对配电网故障类型的及时准确识别有助于故障定位和事故分析等。提出一种基于奇异值分解(SVD)和多级支持向量机(SVM)的配电网故障类型识别方法。首先通过希尔伯特-黄变换(HHT)带通滤波算法对三相电压/电流、零序电压等7个故障波形进行等频宽分解,构造时频矩阵。然后将时频矩阵SVD得到的部分有效奇异值作为特征量,输入到多级SVM进行训练和分类识别。利用PSCAD/EMTDC软件搭建10 k V配电网模型用于获取训练样本和测试样本。测试结果表明,该方法对配电网单相接地、两相接地、两相短路、三相短路等10种故障类型的识别正确率较高,且在噪声干扰、采样不同步、系统网络结构改变、负荷电流变化、系统中性点经消弧线圈接地、系统等值阻抗变化、分布式电源接入等情况下均有较好的适应性。     

Novel Salt-Assisted Combustion Synthesis of High Surface Area Ceria Nanopowders by An Ethylene Glycol-Nitrate Combustion Process

Ceria and ceria-based powders are candidate ma-terials for a wide range of applications ,for example ,solid electrolytes for solid oxide fuel cells (SOFC)[1],three way catalysts for the treatment of automotive ex-haust gases[2],petroleum-cracking catalyst[3],oxygensensors[4], chemical-mechanical polishing for micro-electronics[5],and UVfilter[6].In recent years , since high surface area ceriananoparticles show superior physical and chemicalproperties to bulk particles , much effort has been …     

全数字控制单相AC-DC功率电路设计

针对功率因数、效率、电压、电流等关键指标,以dsPIC33FJ16GS502单片机为控制器,采用单相全桥PWM整流和Buck两级拓扑结构,设计了全数字控制单相AC-DC功率电路。同时具有测量功率因数和输出电流大于2.5 A时过载保护功能,还能实现输入功率因数可调。通过试验测试结果证明系统指标满足设计要求。     

变电站10kV开关柜运行环境监控系统设计

针对变电站10k V开关柜内部的防火泥封堵情况和温湿度等运行环境难以实时掌握和控制,存在安全隐患的问题,设计了一套变电站10k V开关柜运行环境监控系统。该系统的网络架构基于无线传感器网络和以太网混合而成。各个监控终端通过无线传感器网络与通信管理机进行信息交互,通信管理机通过以太网与上位机软件进行通信。本文结合变电站10k V开关柜内特殊的运行环境阐述了该系统的软硬件设计、无线传感器参数配置、上位机软件设计等。     

纳米钕基氧化物的溶胶-凝胶法制备及其催化性能

采用乙二醇溶胶-凝胶法制备氧化钕基氧化物纳米粒子,研究乙二醇与Nd3+的摩尔比、煅烧温度和掺杂对产物结构的影响及其对高氯酸铵热分解的催化性能。研究表明:当乙二醇与Nd3+的摩尔比为10,70℃加热回流2 h,90℃干燥26 h,700℃煅烧2 h,可得到平均粒径为43.6 nm的球形纳米氧化钕;3.4 mol%Mn掺杂Nd2O3纳米粉体催化高氯酸铵热分解使其在310~350℃和400~470℃的2个小放热峰合并为一个以347.7℃为中心的强放热峰,表观分解热由515 J/g上升到1 250 J/g,高于纳米Nd2O3催化下的1140 J/g,证明了Mn2+掺杂可进一步提高纳米Nd2O3的催化活性。更多还原     

粉末药型罩材料及其工艺技术的研究进展

粉末药型罩的选材和制造工艺已成为国际冲击工程界的研究热点。本文主要总结了国内外相关领域的研究现状。着重讨论了适当引入W、Co、Ni、Bi、Ta等金属材料对以Cu粉为主体的粉末药型罩密度、成型、能量及破甲性能的影响,并且对比了相同材料、不同加工工艺对粉末药型罩微观结构和射流质量的影响。展望了粉末药型罩的发展方向和应用前景,认为通过对传统药型罩材料和工艺技术的改进来制造含能药型罩是粉末药型罩发展的主要趋势。     

Preparation of Well Dispersed and Ultra-Fine Ce （Zr）O2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.