110kV线路距离保护装置的研制

介绍一种基于数字信号处理器(DSP)的新型高压输电线路微机保护装置。它采用多CPU结构,以距离保护和零序保护为主保护,在软件方面应用多种智能化技术,提高了保护性能,详细介绍了保护的主要技术特点。动模测试结果表明,该装置整体性能优良,能够满足110 kV线路对距离保护的要求。     

Enhancing the ferromagnetization of graphite by successive C ion implantation steps

¹²C⁺ ion implantation has been shown to be an efficient way to increase the magnetization of highly oriented pyrolytic graphite, and a saturation magnetization of 17.6 emu g⁻¹ at room temperature has been produced. The implantation was performed in four steps with decreasing ion energy for each step. Increasing the magnetization with the number of implantation steps has shown that the magnetization is correlated to the defect density. The temperature dependence of spin susceptibility calculated according to the electron spin resonance spectra indicates that the magnetism in the sample is intrinsic. The evolution of Raman spectra along with the degree of implantation supplied further evidence to the correlation between in-plane defects and the magnetization of the sample, and explained the decreased magnetization resulting from the final implantation step.     

对低压接地相关标准的异议

低压系统和用户直接关联,合适的接地方式对于保障设备和人身安全具有重要作用。国内低压配电系统接地标准的制定长期没有得到重视,部分标准存在较多问题。为此,文中广泛查阅了国内外低压系统接地相关标准,并进行了对比分析,对其中不一致或矛盾之处进行了辨析;结合IEC相关标准,指出了国内标准存在的不合理之处,涉及名词术语的使用、"零线"重复接地以及变电所共用接地等,明确了重复接地和共用接地的适用条件,并提出了修改建议。     

Experimental study on permanent deformation characteristics of coarse-grained soil under repeated dynamic loading

Practical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading. In this paper, repeated load triaxial tests were performed on coarse-grained soil (CGS), and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed. Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory. A prediction model of permanent deformation considering stress state and number of load cycles was established, and the ranges of parameters for different types of dynamic behaviors were also divided. The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS. The stress state (confining pressure and dynamic stress amplitude) has significant effects on the permanent strain rate. The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function, and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude. The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.

     

微生物油脂提取技术的研究进展

该文介绍了微生物油脂的组成特点、国内外研究现状、生产工艺,着重叙述主要提取方法,包括超临界CO2萃取法、有机溶剂萃取法、索氏抽提法、酸热法、酶解辅助萃取、超声波辅助萃取、反复冻融辅助萃取和微波辅助萃取,分析论述了这些方法对产油微生物油脂萃取率的影响,同时总结了这些提取方法的原理、优点和研究现状,并分析了微生物油脂提取技术的发展趋势。     

基于SAXS方法的核石墨微孔结构的温度影响

X射线小角散射(Small Angle X-ray Scattering,SAXS)是研究纳米尺度微观结构的重要手段。本文利用同步辐射SAXS技术测量了25oC、100oC、200oC、300oC和400oC时,IG-110和NBG-18核石墨在纳米尺度范围内孔隙的数量分布及其分形特征的变化。实验结果表明,IG-110和NBG-18核石墨的微观结构中存在微小尺寸上的不均匀区域,且核石墨孔隙的固气结构具有明锐的界面。但随着温度的升高,固气界面的变化并没有呈现出明显的规律性。此外,在纳米尺度上,IG-110和NBG-18核石墨的孔隙数量随温度呈现增加的趋势,且IG-110核石墨孔隙数量的增加幅度大于NBG-18核石墨,其平均孔隙尺寸的减小幅度大于NBG-18核石墨。在核石墨的微孔结构内,其固气界面的分形维数随温度升高逐渐减小,且NBG-18核石墨分形维数的变化幅度小于IG-110核石墨。这表明核石墨的分形结构随温度的升高逐渐光滑。     

高效降亚硝酸盐乳酸菌的驯化复筛及菌株鉴定

目的：筛选出高效降亚硝酸盐乳酸菌,为今后益生乳酸菌的开发提供一定的理论依据。方法：从地方特有食品及动物肠道中分离纯化出13 株乳酸菌,采用盐酸萘乙二胺法对13 株乳酸菌的体外降亚硝酸盐能力进行测定,并对降亚硝酸盐效果最强菌株进行驯化培养和抑菌实验,通过生理生化及16S rDNA法对所分离的降亚硝酸盐能力最强菌株进行鉴定。结果：获得1 株编号为JS3的乳酸菌,该菌对亚硝酸盐降解率为83.39%,经过驯化复筛及培养条件优化得到：培养基中蛋白胨添加量15 g/L、接菌量5%、培养温度30 ℃、培养时间48 h,其降解率达到93.47%,同时菌株对金黄色葡萄球菌和枯草芽孢杆菌还具有抑制性能。经鉴定菌株为玉米乳杆菌（Lactobacillus zeae）,将其命名为L. zeaeJS3。结论：菌株JS3具有高效降解亚硝酸盐能力,能够成为今后降解亚硝酸盐微生态活性菌的优良菌种。     

X射线在碳纳米管(绳)和Fullerites晶体内的传输

近年来发展起来的新毛细管光学聚焦元件由许多根弯曲的多層壁碳纳米管组成,能被用来产生高强度的nm级X射线微束.作为软X射线布拉格(Bragg)衍射传输的新元件,单層壁碳纳米管绳(超晶格结构的晶体)和Fullerites(C60分子晶体)已经引起了世界范围内的研究兴趣.本文介绍这方面的研究进展.     

通信工程传输技术的应用及发展研究

在信息技术的飞速发展下,通信工程取得了长足发展,且对传输及时性的要求也越来越高。分别从通信工程的两个重要领域（长途干线传输网和本地骨干传输网）和传输技术的两种主要技术（光纤传输技术和无线传输技术）这两个角度出发,探讨了当前通信工程传输技术的应用情况,并分析了其未来的发展趋势。     

基于微纳层叠共挤的PLA/PCL可降解微层薄膜的制备及性能研究

采用微纳层叠共挤出设备制备聚乳酸（PLA）/聚己内酯（PCL）可降解微层薄膜,利用扫描电子显微镜、万能材料试验仪、差示扫描量热仪和热失重分析仪等对微层薄膜的微观结构、力学性能和热稳定性进行表征。结果表明,PLA/PCL微层薄膜的热稳定性和力学性能均优于PLA/PCL共混薄膜;PCL对微层薄膜具有明显的增韧效果,同时可提高微层薄膜的结晶性能和热稳定性;当PLA/PCL配比为40/60、50/50或60/40时,PLA/PCL微层薄膜具有良好的综合性能,此时拉伸强度高于51.2 MPa,断裂伸长率高于568.6 %,冲击强度高于100.7 J/m,微层薄膜中PLA相的结晶度高于43.28 %、热降解峰值温度高于373.22 ℃。