关于中压电缆网双环接线方式供电能力的分析

结合北京地区现阶段对相关技术的规定,以实际供用电方案为例,对中压电缆网双环接线方式的供电能力进行深入讨论。通过设计环网单元划分,发现某些条件下双环网供电能力可以得到进一步提升。     

提高小水电线路重合闸成功率探讨

小水电具有无污染、分布广等特点,在农村或偏远山区应用广泛。但小水电难以迅速调节自身的功率,在因故障跳闸而形成孤岛时,容易导致重合闸失败。通过阐述、分析当前小水电并网重合闸的原理和现状,归纳了影响重合闸成功率的相关因素,以期为电网的安全、稳定运行作出贡献。     

计算机网络安全威胁的技术特征与防范措施

目前,在计算机网络中存在许多不安全因素,这些因素不仅会对计算机的正常运行造成影响,还会对社会发展造成较大的影响.因此,我们要结合具体情况,采取有针对性的防范措施.简要分析了计算机网络安全威胁的特征和防范措施,希望可以为相关单位提供一些有价值的参考意见.     

Mechanical and ablation properties of 2D-carbon/carbon composites pre-infiltrated with a SiC filler

In order to improve the mechanical and ablation properties of 2D-carbon/carbon composites, a SiC filler was added to a 2D-preform before isothermal chemical vapor infiltration densification by using a powder infiltration technique. Backscattered electron images showed that the SiC filler was mainly concentrated between the fiber bundles and between the layers. The tensile and flexural strengths of the composites were improved by the addition of the SiC filler because of the increase of interfacial surface areas between the bundles and between the layers, the less residual open porosity, and also the strong bonding between the SiC particles and the pyrocarbon matrix. The composites with filler experienced a 15.2% lower thickness erosion rate and a 51.7% lower mass erosion rate, compared to those C/C without filler. This was attributed to the low oxygen permeability of the SiO₂ shielding the exterior inter-bundle pores as well as to a thermal barrier effect.     

剑麻纤维／酚醛树脂复合材料研究

本文采用碱处理、硅烷偶联剂处理、化学接枝和热处理等物理化学方法，对剑麻纤维进行改性。研究了改性后短剑麻纤维／酚醛树脂复合材料的弯曲性能、无缺口冲击强度和布氏硬度，借助扫描电子显微镜观察了复合材料的弯曲断口形貌，并研究了剑麻纤维的不同处理方法对复合材料耐水浸泡性的影响。结果表明：剑麻纤维经硅烷偶联剂处理后，能有效改善刚性的剑麻纤维与脆性的酚醛树脂基体之间的粘结，从而提高了复合材料的综合力学性能，剑麻     

陕西秦岭山地体育旅游资源特征及开发模式分析＊

体育旅游作为一种新兴的旅游产品,正在慢慢走近人们的生活中。它将体育与旅游结合起来,在满足了人们休闲旅游需求的同时,也锻炼了身体,因此,受到了许多人的青睐。特别是山地体育旅游,它已经成为了广大旅游者的首要选择。在山地体育旅游蓬勃发展的大背景下,着重研究了陕西秦岭的山地体育旅游资源,分析了它的优势,并提出了合理的建议,以促进山地体育旅游的发展。     

国产软硬件环境下图像组织浏览构件设计

针对在国产软硬件环境下,应用系统读取、浏览大量图像数据的速度慢问题,设计了图像组织浏览构件。通过改进图像组织方式,将基础影像和目标对象图像分开组织管理,并对目标对象图像的属性和分层、分类进行探讨,实现图像信息的快速展现。对图像组织浏览构件进行了插件化设计与实现,利用QT跨平台开发工具,实现了应用集成框架,并通过实现统一集成接口,进行各业务插件的集成。     

Preparation and protein adsorption of hydrogel polysucrose microspheres

A series of novel hydrogel polysucrose microspheres with the mean size ranging from 200 to 500 μm were prepared via two‐step method. First, soluble polysucrose was synthesized by solution polymerization between sucrose and epichlorohydrin; second, a reversed phase suspension crosslinking reaction was performed to prepare polysucrose microspheres. The SEM images indicated that these spherical beads had smooth surface and hydrogel interior structure. FTIR was used to characterize the chemical structure of the beads. The hydrated and dry densities, equilibrium water content, and hydroxyl content of polysucrose microspheres were also investigated. The characteristic of high hydroxyl content (15.48–19.04 mmol/g) make these microspheres suitable for protein adsorption. Meanwhile, bovine serum albumin was used to examine the adsorption capacity of the microspheres. These microspheres had a capacity as high as 49.28 mg/g. The adsorption kinetics and recycling of the beads were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5934–5940, 2006     

Feeding pure docosahexaenoate or arachidonate decreases plasma triacylglycerol secretion in rats

Essential fatty acid (EFA)-deficient rats were fed highly purified methyl esters of docosahexaenoate (22∶6n−3), arachidonate (20∶4n−6), alpha-linolenate (18∶3n−3) or oleate (18∶1n−9) (100 mg/day, tube fed for 3–10 days), and their plasma triacylglycerol (TG) secretion rates were measured. Secretion rates of TG into plasma were reduced by tube-feeding 22∶6n−3, 20∶4n−6, 18∶3n−3, but not 18∶1n−9, to EFA-deficient rats. A significant reduction occurred after feeding 22∶6n−3 for only three days. Feeding 22∶6n−3 or 18∶3n−3 to EFA-deficient rats for three days also reduced the activities of liver lipogenic enzymes and sharply increased the proportions of 22∶6n−3 and 20∶5n−3 in liver phospholipid fractions. Mechanisms by which these EFA may reduce lipogenesis are discussed.     

弹性纳米粒子/纳米TiO2/聚丙烯复合材料的研究

采用专利技术制备了弹性纳米粒子(ENP)／纳米二氧化钛(TiO2)复合材料，并使用这种复合材料改性聚丙烯(PP)，制备了具有较高韧性和较好灭菌性能的PP纳米复合材料。当丁苯ENP的用量为2％，平均粒径为50nm的金红石型TiO2用量为1％时，所研制的PP纳米复合材料的冲击强度可提高30％以上，灭菌率可达60％。