Gas flow through highly porous graphite matrices

Highly porous graphite matrices with 20-200 kg m⁻³ of bulk densities have been characterized using helium pycnometer, mercury porosimeter, and fluid flow methods, i.e. both gas permeation and diffusion measurements. The gas permeability is ranging from 10⁻¹² to 10⁻¹⁵ m² and decreases as the bulk density of the graphite matrix increases. According to the Carman-Kozeny correlation, the evolution of the gas permeability with respect to the bulk density is very well correlate with, on the one hand, the increase of the tortuosity, and on the other hand, the decrease of the porosity as well as the pore diameter with the bulk density of the graphite matrix.     

新IT基础架构探讨

在互联网时代,各行业需要在"商业模式"和"体验"方面的创新,这使得IT变成了核心引擎,需要新的IT基础架构。     

Microscopic study of failure mechanisms in infiltrated carbon fiber felts

Failure mechanisms in infiltrated carbon fiber felts have been studied by optical light microscopy, transmission electron microscopy and scanning electron microscopy combined with mechanical testing experiments. A model is presented which describes crack generation and propagation at layer-layer and fiber-matrix interfaces as well as within matrix carbon layers with different textures. Intensive cracking occurs within high- and less frequently in medium- and low-textured pyrolytic carbon layers. In particular, fracture does not occur directly at the fiber-matrix interface but within the low-textured matrix layer deposited on the fiber. Crack deflection in interface regions between layers with different textures, crack deflection along boundaries of columnar grains in high -textured layers and at interfaces between polyhedral nanoparticles, and finally crack bridging within high -textured lamellae are cooperative failure mechanisms contributing to the toughness enhancement.     

职业技能考证项目培训课程的网络教学融合应用与创新

以Moodle平台为依托,为职业技能考证实训教学环节构建了一个引领学生在线自主学习的网络模式,其主要特色是以课程理论为基础,以校企参与制定的人才培养计划作为主要课程内容,以合作企业作为教学的组织形式,并且将三者有机融合形成体系,以此进行理论与实际的一体化教学;同时融合网上异步教学理念形成一套崭新的教学模式。     

Scrolls and nested tubes in multiwall carbon nanotubes

Recent high-resolution transmission electron microscopy (HREM) studies of multiwalled carbon nanotubes (MWCNTs) reveal a class of defects analogous to edge dislocations in a crystal. These defects are believed to mark the transition from scrolls on one side to nested tubes on the other. On the tube side, layer spacing becomes irregular. Analysis of the helicity of the tubes shows a strong correlation between diameter and helicity. This suggests that the organizing principle for the tubes is not Van der Waals forces, as in the case of graphite or turbostratic carbon, but preservation of helicity. Based on these observations and total energy calculations, the authors speculate that graphene monolayers initially form scrolls and subsequently transform into multiwall nanotubes through the progression of defects. Scrolls and nested tubes thus coexist within a single MWNT.     

Word的高级应用——制作表单

通过实例,详细讲解用Word的窗体工具建立表单,以解决行政部门制作电子文档的空白表格时,让填写的人员方便、快捷地填写内容,又不随意修改(破坏)原有格式和原文。     

对计算机网络信息教育教学的反思

计算机教育的发展,为社会输送了具备较高理论素养及较强操作技能的新型网络技术人才,同时,针对新时期网络信息教育,在面向信息技术时代仍凸显一些问题。通过分析计算机网络信息教育教学中存在的若干问题,对教育教学的继续发展进行深入反思。     

磺酰胺类除草剂阔草清的合成研究

以5-氨基-3-巯基-1，2，4-三唑和2，6-二氟苯胺为主要原料，经苄基化、环合、酰化、胺解4步反应合成阔草清，总收率46．5％。该方法可以降低成本，提高反应速度，简化分离步骤，降低能耗和减少污染，是一种较清洁的生产工艺，适合工业化生产。     

Corrosion and mechanical behavior of fusion bonded epoxy (FBE) in aqueous media

In recent years there have been many reported cases of corrosion failure in cement concrete pipelines. In the majority of cases, the failures have been attributed to rebar corrosion which is caused by the permeability of chloride from low resistivity soil and subsequent attack on a passive layer on an iron bar in the structure. As a possible alternative to cementitious materials, some organic coatings based on olefin, vinyl or epoxy-based polymers have been considered. However, due to a paucity of data on the behavior of these coatings in aqueous media— particularly product water—the possibility of their application in water transmission systems in the Kingdom has not been fully exploited. This paper deals with the studies carried out on the corrosion and mechanical behavior of fusion bonded epoxy (FBE) coating on steel in aqueous media which include product water, distilled water and saline water. The mechanical testings on coating include adhesion, bending and cathodic disbondment testings. The corrosion studies include immersion testing under static and dynamic conditions, autoclave tests and accelerated (salt-fog) tests. The analysis of results indicates chemical inertness of FBE coating in either of the aforementioned water used during testing, good adhesion and no damage to the coating during bending. Cathodic disbondment tests indicate that FBE coating sustains under cathodic protection (CP) conditions. In general, the results of mechanical and corrosion tests indicate that FBE is a promising material for internal coating on steel in water transmission systems.     

智能手机点击劫持攻击检测方法研究

点击劫持通过欺骗用户点击经过伪装的界面元素达到攻击目的。移动互联网环境下,智能手机的屏幕特征、手势识别、HTML5支持度高等特性成为点击劫持新的利用点。深入分析并实验验证智能手机脆弱特性,在此基础上提出点击劫持在智能手机上的潜在攻击方案。进而设计并实现一套有针对性的检测方案。该方案从静态页面和动态行为两个角度提取攻击特征,并进行基于规则的量化评估与组合判定。实验结果表明该方案可以有效地降低传统页面特征检测方案的漏报和误报情况。