对皖北地区500kV输电线路耐雷性能的研究

根据安徽电网皖电东送通道8条500 kV线路的运行情况,结合皖北地区500 kV输电线路跳闸原因,分析输电线路设备耐雷状况,提出了综合防治措施,以便改进皖北地区500 kV线路的耐雷性能,提高其安全稳定运行水平。     

挤压模障碍角作用误区

型材挤压的流动均匀性关系到制品尺寸的稳定性，目前常用的控制流动的方法是调整挤压模工作带的大小，采用先导模，扁挤压筒，开促流角，障碍角等措施。开障碍角的办法由于其自身的可操作性问题和增加阻力机理不明确，并没有广泛地应用。作者针对这一情况对障碍角的作用从模拟实验和理论角度进行了探讨，分析并指出了障碍角作用的误区。     

半不连续切屑流动速度的系统分析及切屑变形的度量

本文借助影片运动分析仪,对用高速摄影记录的钛合金切屑沿前刀面的流动规律进行了研究,并用系统分析法进行了描述,推导出能反映半不连续切屑不均匀变形过程的动态衡量参数,同时也导出了度量此种切屑塑性变形的准静态参数——等效切削比。     

多波束条带测深中的声线跟踪技术

海洋环境里声速随着盐度、温度和深度以及其他因素的变化而变化，导致声波并不沿直线传播，利用声波到达海底某区域的往返时间和声线离换能器的出射角计算该区域的海底深度时，如果采用固定声速，则必然带来误差。为提高测深精度，有必要进行声速补偿，为此，研究一种在深度方向上采用声线跟踪技术进行补偿以提高海底深度测量精度的方法，叙述了射线跟踪的基本原理，进行了计算机仿真，并利用海试数据进行了相应的处理。结果表明，依据声速的变化进行声线跟踪可以大大提高测深的精度。     

基于倾角测试的桥梁变形实时监测研究

对基于结构的倾角测试能实时、精确得到结构变形,以悬臂梁及简支梁为例,推导倾角与挠度间关系,利用MATLAB编程工具对倾角进行积分、拟合得到结构变形,并通过钢梁加载试验与实测挠度进行对比,通过健康监测工程实例介绍倾角仪在变形监测中的应用。分析表明,建立的倾角和变形间关系合理可行,不同结构进行变形监测需考虑边界条件;基于MATLAB对倾角拟合挠度曲线过程简单,与实测挠度吻合较好;在桥梁健康监测系统中用倾角仪对结构进行变形监测,可得结构实时变形曲线与任一时刻变形规律。     

西南桦木包装材料在热处理后的润湿性能研究

通过动态接触角测量、红外光谱分析、表面粗糙度测量、扫描电镜观察和偏相关分析,研究了西南桦木的润湿性能。结果表明,木材经180℃热处理4 h后,润湿性能下降:接触角由40°增至121°,羟基和羰基数量减少,粗糙度降低;处理时间与接触角显著相关;西南桦木用作包装材料,若采用热处理,可去除有害生物,还具备疏水功能。     

Order vs. Disorder: Cholesterol and Omega-3 Phospholipids Determine Biomembrane Organization

Lipid structural diversity strongly affects biomembrane chemico-physical and structural properties in addition to membrane-associated events. At high concentrations, cholesterol increases membrane order and rigidity, while polyunsaturated lipids are reported to increase disorder and flexibility. How these different tendencies balance in composite bilayers is still controversial. In this study, electron paramagnetic resonance spectroscopy, small angle neutron scattering, and neutron reflectivity were used to investigate the structural properties of cholesterol-containing lipid bilayers in the fluid state with increasing amounts of polyunsaturated omega-3 lipids. Either the hybrid 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or the symmetric 1,2-docosahexaenoyl-sn-glycero-3-phosphocholine were added to the mixture of the naturally abundant 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and cholesterol. Our results indicate that the hybrid and the symmetric omega-3 phospholipids affect the microscopic organization of lipid bilayers differently. Cholesterol does not segregate from polyunsaturated phospholipids and, through interactions with them, is able to suppress the formation of non-lamellar structures induced by the symmetric polyunsaturated lipid. However, this order/disorder balance leads to a bilayer whose structural organization cannot be ascribed to either a liquid ordered or to a canonical liquid disordered phase, in that it displays a very loose packing of the intermediate segments of lipid chains.     

PAN基原丝预氧丝炭纤维微结构的几种新的X射线衍射散射定量表征技术

介绍几种新近开发的针对PAN基原丝、预氧丝和炭丝微结构和结构缺陷的X射线衍射与散射定量表征技术,它们是:纤维材料中柱状(椭球状)纳米取向微孔体积分数X射线小角散射定量表征方法;纤维材料中柱状(椭球状)纳米取向微孔取向角的小角散射定量表征方法;预氧丝中链状相与环化相体积分数的小角衍射定量表征方法以及炭纤维中乱层石墨相与单层石墨相的X射线广角衍射定量表征方法等。     

抽出式风机在治理工作面上隅角瓦斯的应用

针对漳村煤矿综采工作面上隅角瓦斯浓度高的情况,用抽出式风机处理上隅角瓦斯,较好地解决了上隅角瓦斯频繁超限事故,实现了矿井的安全生产。     

Fractal characteristics of electric properties of coal

In the light of fractal geometry theory, the characteristics of coal＇s electric parameters （including dielectric constant, alternating conductivity, dielectric loss angle tangent and electric polarization constant） were studied by using literature data. The results are shown that the electrical properties of coal have fractal characteristic. The fractal dimensions of dielectric, alternating conductivity, dielectric loss angle tangent were obtained, and are relative to the content of pyrite sulfur, heat and ash content of coal.