20MnCr5圆棒锯切困难原因分析

某厂在锯切20MnCr5圆棒过程中锯条容易断裂，采用光学显微镜(OM)和扫描电子显微镜(SEM)等观察分析手段，对锯条容易断裂的原因进行分析。分析结果表明：锯条断裂的原因为加工20MnCr5过程中粘刀崩齿。针对此类加工缺陷，提出了相应的改进措施。     

2种侧围加强内框总成检具结构对比分析

概述了侧围加强内框总成与周边零件的匹配关系,从检具操作的人机工程出发,描述了侧围加强内框总成检具的2种定位方式和结构设计,对比了2种定位方式对于检测结果的影响,总结了其优点和弊端,结果表明侧围加强内框总成检具采用车内方向朝下的定位方式效果更好。     

Spontaneous Directional Self-Cleaning on the Feathers of the Aquatic Bird Anser cygnoides domesticus Induced by a Transient Superhydrophilicity

In nature, the feathers of the goose Anser cygnoides domesticus stay superhydrophobic over a long term, thought as the main reason for keeping the surface clean. However, contaminants, especially those that are oleophilic or trapped within textures, cannot be removed off the superhydrophobic feathers spontaneously. Here, a different self-cleaning strategy based on superhydrophilic feathers is revealed that is imparted by self-coating of the amphiphilic saliva, which enables removing away low-surface-tension and/or small-size contaminants by forming directional water sheeting depending on their unique anisotropic microstructures. Particularly, the surface superhydrophilicity is switchable to superhydrophobicity upon exposure to air for maintaining a clean surface for a long time, which is further enhanced by coating with self-secreted preening oil. By alternate switching between a transient superhydrophilicity and a long-term stable superhydrophobicity, the goose feathers exhibit an integrated smart self-cleaning strategy, which is also shared by other aquatic birds. An attractive point is the re-entrant structure of the feathers, which facilitates not only liquid spreading on superhydrophilic feathers, but also long-term stability of the cleaned surface by shedding water droplets off the superhydrophobicity feathers. Thus, artificial self-cleaning microtextures are developed. The result renews the common knowledge on the self-cleaning of aquatic bird feathers, offering inspiration for developing bioinspired self-cleaning microtextures and coatings.     

不同细颗粒含量甲烷水合物沉积物三轴剪切试验研究

海域试开采区域含水合物沉积物的粒度分析结果表明水合物沉积物骨架由粗、细颗粒混合构成,通过开展多组低温、高压三轴排水剪切试验研究细颗粒含量和密度对含甲烷水合物沉积物和无水合物沉积物的强度和变形特性的影响。试验结果表明,含水合物沉积物抗剪强度及剪胀性都随细粒含量提高而显著增强。这是由于细颗粒含量增加改变了颗粒间水合物的样貌和分布特征,形成了由水合物包裹着粗颗粒-细颗粒的团簇状集合体。然而,细颗粒含量对无水合物沉积物的强度和变形特性的影响却表现出相反趋势。另外,含水合物沉积物的剪胀关系可以使用修正剑桥模型中的剪胀关系式进行描述。结果表明,剪胀关系的拟合曲线依赖于水合物饱和度的大小。通过对比研究发现,天然水合物和实验室合成水合物试样在较高饱和度时的峰值摩擦角大小及其伴随水合物饱和度的增长趋势存在差异,这种差异主要来源于水合物在沉积物骨架颗粒孔隙中不同的赋存模式及分布特征。     

对称极坐标牛顿法潮流的直角坐标解法

为综合利用极坐标牛顿法潮流方程数少、雅可比矩阵J元素少以及直角坐标牛顿法中没有三角函数计算的特点,并克服极坐标牛顿法潮流J阵元素的不对称使其计算速度不理想的情况,提出一种对称极坐标牛顿法潮流的直角坐标解法.主要内容为,建立结构不完全对称的子阵形式的极坐标J阵,通过子阵建立子阵元素间的对应关系;拆分J阵元素的计算,建立子阵元素的部分对称关系;对J阵元素等计算公式进行三角变换,并按"二行+二列"的对称方式计算J阵元素;用四角规则而不是消元计算公式对J阵元素消元;将取倒的对角元素作为规格化因子以减少除法计算.新方法不但可实现J阵元素的部分对称计算,还可大量减少三角函数的运算以及消元过程中的除法运算,且无需计算公式直接完成消元计算.以IEEE-118节点系统为例,新方法生成J阵速度可提高约90％以上,潮流计算速度可提高约30％,并极利于编程.     

有机-无机压电材料TMCM-MnCl3的研究

有机-无机压电材料是一种分子铁电体，具有柔性、结构灵活、易成膜、全液相合成及环保节能等优点，可满足新一代薄膜器件及可穿戴设备的需求。该文以三甲基卤代甲基铵(TMXM, X=F, Cl, Br)为有机部分，MnCl₂为无机部分，通过溶液蒸发法制备了具有钙钛矿分子结构的有机-无机压电材料三甲基氯三氯化锰(TMCM-MnCl₃)，并对其分子结构组成、压电、热学、声学及铁电性进行表征。结果表明，TMCM-MnCl₃的压电常数为106 pC/N，居里温度为130 ℃，声阻抗值约为16.5 MRayl，低于压电陶瓷PZT-4(大于33 MRayl)，具有广阔的应用前景。     

Preparation of a ternary hybrid of P-g-C3N4@PGS-Ti and its enhancement of the flame retardancy of epoxy resins

A novel ternary hybrid flame retardant named P-g-C₃N₄@PGS-Ti was prepared through step-by-step method. First, titanium dioxide was loaded on PGS to make PGS-Ti (where PGS = palygorskite), and then, PGS-Ti was decorated by phosphor-doped g-C₃N₄ (abbreviated as P-g-C₃N₄) to prepare a ternary flame retardant of P-g-C₃N₄@PGS-Ti. It showed that P-g-C₃N₄@PGS-Ti could efficiently improve the flame retardancy of epoxy resins (EP). The structure and the morphology of P-C₃N₄@PGS-Ti were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scaanning electron microscopy and hermogravimetric analysis (TGA). The flame retardancy and the burning behavior of 5 wt% P-g-C₃N₄@PGS-Ti composited EP were well investigated through TGA, limiting oxygen index (LOI), cone calorimeter test (CCT) and vertical burning test (UL-94 standard). It was found that the peak heat releasing (pk-HRR) of the EP/P-g-C₃N₄@PGS-Ti composite reduced 36% (from 1459 to 852 kW/m²) with the addition of 5 wt% of P-g-C₃N₄@PGS-Ti flame retardant to the matrix of EP. The combustion residue analysis showed that the EP/P-g-C₃N₄@PGS-Ti composite gained the most continuous and firmest char yield due to the synergistic effect of PGS, TiO₂ and the introducing of P element. The mechanism proved that the combination of gas phase and condensed phase flame-retardant processes were well coordinated to improve the fire retardancy for EP. We tested and studied the mechanical properties of EP/P-g-C₃N₄@PGS-Ti composites. Only 2.4% decreasing of flexural strength and 23.5% decreasing of impact strength in EP/P-g-C₃N₄@PGS-Ti composites compared to pure EP, respectively. But according to the test results of EP/P-g-C₃N₄@PGS-Ti composite material and the control sample in the system, EP/P-g-C₃N₄@PGS-Ti composite material had the highest flexural modulus and impact strength.     

黄芩苷印迹聚合物在银黄口服液质量分析中的应用

从天然产物和中草药中选择性提取生物活性化合物是困难的,但对药物分析和新药开发是必要的也是亟需的.该研究采用沉淀聚合法,以黄芩苷为模板分子,与丙烯酰胺和乙二醇甲基丙烯酸共聚,以N、N-二甲基甲酰胺为致孔剂合成了分子印迹聚合物,与非印迹聚合物相比,制备的分子印迹聚合物具有良好的选择性,并用于银黄口服液的质量分析.结果表明:该分子印迹聚合物能从复杂基质中选择性提取黄芩苷及其结构类似物.