纳米添加剂与几种常用添加剂的复配性研究

文章采用往复摩擦磨损试验机考察了纳米铜复合超细蛇纹石微粉与摩擦改进剂(MoDTC)及清净分散剂(T106)复配体系的摩擦学性能,借助扫描电子显微镜观察了试样磨痕表面形貌,并研究了添加剂的作用机制。结果表明:当该纳米添加剂、MoDTC与T106按一定质量分数的比例复配加入基础油后,其摩擦系数大幅度降低,抗磨性能得到明显提高,具有极好的摩擦学性能。     

新疆“昆仑金玉”的宝石矿物学特征

采用X射线粉末衍射、傅里叶红外吸收光谱、原子吸收光谱、扫描电子显微镜及宝石学常规测试等分析方法,对具有代表性的两种颜色的新疆"昆仑金玉"样品的宝石矿物学特征进行了深入研究。结果表明,"昆仑金玉"的矿物组成为蛇纹石,深绿色品种为叶蛇纹石,黄绿色品种为利蛇纹石,深绿色品种的硬度高于黄绿色品种;"昆仑金玉"的颜色与Fe元素的质量分数密切相关,黄绿色品种中Fe的质量分数高于深绿色品种,其中,不同的Fe~(3+)/Fe~(2+)比值致"昆仑金玉"呈现不同的色调;深绿色品种中的叶蛇纹石和黄绿色品种中的利蛇纹石在扫描电子显微镜下均展现典型的片状外观,深绿色品种中的叶蛇纹石边缘为参差状,而黄绿色品种中的利蛇纹石发育圆化的边缘,这种形态的差异说明两种蛇纹石具有不同的内部结构。红外光谱结果显示,3 644cm~(-1)处"肩状"吸收峰的出现,说明深绿色品种中的叶蛇纹石和黄绿色品种中的利蛇纹石具有不同的内部结构。     

X荧光熔融分析蛇纹石方法研究

对蛇纹石X荧光熔融分析方法进行了研究.采用滑石、镁砂等标准样品,配制成蛇纹石标准系列,用于蛇纹石检测.蛇纹石含有一定量的结晶水,熔融后,同样的含量,因稀释后的体积不同,将产生偏差,通过校正,提高了检测结果的准确性.     

蛇形管内汽液泡状流与传热的数值模拟

建立了含有相变过程的汽液泡状流VOF数值模型,通过同实验进行流型对比,验证了模型的有效性。模拟研究了蛇形管内汽液泡状流传热过程,结果表明：二次流导致冷热流体混合;在单汽泡流动时,弯管壁面上温度场在汽泡经过后具有良好的恢复能力;在汽泡串流动时,二次流将弯管下半部温度较高的流体带入上半部,有效提升上半部壁温,从而造成上壁面温度在汽泡经过前后出现较大的变化。     

Design of thermal management subsystem for a 5 kW polymer electrolyte membrane fuel cell system

High-efficiency thermal management subsystem has a key role on the PEM fuel cell performance and durability. In this study, design of thermal management subsystem for a 5 kW PEM fuel cell system is investigated. A numerical model is presented to study the cooling flow field performance. The number of parallel channels in parallel serpentine flow field is selected as the design parameter of the flow field and its optimum value is obtained by compromising between the minimum pressure drop of coolant across the flow field and maximum temperature uniformity within the bipolar plate criteria. The optimum coolant flow rate is also determined by compromising between different criteria. Test results of a 5-cells short stack are presented to verify the numerical simulation results.     

A tapered serpentine flow field for the anode of micro direct methanol fuel cells

We develop a self-breathing micro direct methanol fuel cell (μDMFC) characterized by a new anode structure with tapered single serpentine flow fields to improve cell performance. Compared with the conventional single serpentine flow field, this new design enhances the methanol mass transport efficiency and the exhaust resultant (CO₂) rate due to the increasing pressure difference between adjacent flow channels. The μDMFCs with two single serpentine flow fields are fabricated using silicon-based micro-electro-mechanical systems (MEMS) technologies and are tested at room temperature. The experimental results reveal that the new tapered single serpentine flow field exhibits a significantly higher peak power density than that of the conventional flow field, demonstrating a substantial increase of 17.9% in mass transport coefficients.     

直接空冷凝汽器翅片管污垢层清洗的数值研究

直接空冷凝汽器翅片管作为空冷单元的重要换热组件,翅片管的清洁程度直接影响空冷单元的高效换热能力。目前对如何提高直接空冷凝汽器翅片管换热能力的研究较多,但是对于直接空冷凝汽器翅片管粘有污垢层后的清洗状况鲜见报道。对此,本文对直接空冷凝汽器蛇形翅片管污垢层清洗进行了数值模拟,分析了翅片管表面具有不同厚度的垢层时,在清洗过程中所受到的压力和剪切应力随时间的变化规律。结果表明：清洗带有不同厚度垢层的翅片管,翅片管表面垢层越薄,就越容易清洗,所需清洗时间越短;翅片管表面垢层受到的压力和剪切应力随垢层厚度的减小而减小,随清洗时间的增加而减小;经计算得出,清洗喷嘴的移动速度为1.1～1.5m/min时可更好的清洗翅片管表面的污垢。     

Rauvolfia serpentina-Mediated Green Synthesis of CuO Nanoparticles and Its Multidisciplinary Studies

Copper oxide nanoparticles(Cu O Nps) were successfully synthesized by solution combustion method using aqueous leaf extract of Rauvolfia serpentina as a fuel. The structure and morphology of the Cu O nanoparticles(Nps) were characterized by powder X-ray diffraction(PXRD), UV–visible spectroscopy(UV–visible), scanning electron microscopy(SEM), transmission electron microscopy(TEM), etc. The PXRD patterns reveal the formation of monoclinic phase with crystallite structure. SEM images indicate that the particles have sponge-like structure being highly porous and agglomerated with large surface area. The average crystallite sizes were found to be in the range of 10–20 nm by Scherrer's method. The Cu O Nps size was further confirmed by TEM. Further, Cu O Nps exhibit good photocatalytic activity for the photodegradation of trypan blue dye, indicating that it acts as a promising semiconducting material. The antibacterial properties of Cu O nanoparticles were investigated against pathogenic bacterial strains, namely Gram-ve Escherichia coli(NCIM-5051) and Pseudomonas desmolyticum(NCIM-2028) and Gram ?ve bacteria Staphylococcus aureus(NCIM-5022) using the agar well diffusion method.     

六自由度十字关节蛇形机器人运动学分析

基于一种具有十字关节的蛇形机器人,建立了机器人的连杆坐标系,采用D-H法建立了机器人的正向运动学方程,给出了机器人的运动学正解表达式。在此基础上,通过解析法求解了机器人运动学逆解。通过对机器人运动模型进行Simulink仿真,给出了机器人末端的运动空间,对所求解的正确性进行了验证。     

蛇纹岩开发与综合利用

蛇纹岩（除蛇纹玉外）应用时主要加工方法有物理加工、热法（焙烧法）、湿法（酸解法）3种。中国从20世纪90年代开始开发研究蛇纹岩各种应用,不完全统计有关论文575篇,发明专利27项。蛇纹岩的研究领域在拓宽,应用范围在扩大,从农业到医药,耐火材料、建材到化工材料,金属镁和镁化合物、单晶硅到硅化合物系列产品,环保产品到玉石产品,均在快速发展。蛇纹岩将具有更好的开发前景和更高的利用价值。