Advanced Surface of Fibrous Activated Carbon Immobilized with FeO/TiO2 for Photocatalytic Evolution of Hydrogen under Visible Light

FeO-doped TiO₂ nanoparticle photocatalysts were immobilized onto the surface of fibrous activated carbon (ACF) via a sol-gel process. As an adsorbent and photocatalyst, FeO-TiO₂ on immobilized ACFs (FeO-TiO₂/ACF) greatly improved the photocatalysis rate of hydrogen production as compared with pure TiO₂ and ACF-TiO₂ under UV irradiation and visible light. The addition of ACFs surface significantly reduced the photogenerated pairs of electrons-hole recombination, thereby promoting the photocatalysis action of doped photo-metal oxides of FeO-TiO₂. Co-doping of FeO onto the lattice of the TiO₂ approach can improve the absorption activity of visible light through photo-metal oxide of TiO₂ and further enhance hydrogen production under visible light. The photocatalytic fabrics (FeO-TiO₂/ACF) were effortlessly split out from the experimental solution for re-utilization and exhibited high stability even after five complete regeneration cycles.     

智能动态网络资源分配系统

通过对解决GSM移动通信网络热点区域话务拥塞问题的研究，提出了利用可控功分器实现智能动态网络资源的分配，解决不同种类的话务拥塞问题，并着重讨论了该系统目前的成功运用及前景。     

SQL的现状及其研究与发展

一、SQL简介 如果说七十年代关系数据库还处于研制实验阶段,那么到了八十年代大量关系数据库商用产品的面市几乎占据了整个数据库市场,其中的原因在于它们使用了统一的语言界面,那就是,SQL成为了关系数据库的通用语言。 1974年．IBM公司San Jose研究实验室的D．D．Chamberlin在开发SEQUEL-XRM原型时提出了SE-QUEL(Structured English Query Language),1976年又修改成为SEQUEL／2．也就是目前的SQL(StructuredQuer Language)。SEQUEL／2主要成形于IBM的Sys-tem R原型中[2],并在原有基础上大加扩展,其后逐渐完善并最终成为一种完备的结构化数据库查询语言。     

中国珠宝销售的可持续发展

通过对改革开放20多年来中国珠宝业发展的回顾与分析, 认为在激烈的市场竞争中, 珠宝业要达到可持续发展必须具备6个要素: (1)敬业精神; (2)信用意识; (3)创新意识和创新能力; (4)激励机制和团队精神; (5)资本营运和资源整合能力; (6)关系营销技巧.     

Electric field-assisted and field-depressed segregation of reactive metals to the bonding interface in braze alloy joining

Segregation of reactive metals at the bonding interface has been observed in various ceramic and/or metal joints bonded with reactive metal-bearing braze alloys. When a d.c. of 20 mAcm⁻² is applied to the ceramic/braze/ceramic system at a brazing temperature of, say, 1373 K, the electric field assists the segregation at the braze-ceramic interface on the cathode side and suppresses the segregation at the interface on the anode side. This may imply that reactive metal atoms in the braze can migrate as a cation. E.m.f. measurement on the ceramic (AIN or ZrB₂)-metal foil systems with increasing temperature shows that a negative e.m.f. to the ceramic pole appears from about 900 K for AIN and from 500 K for ZrB₂, as does the thermally stimulated current in polymers. These temperatures coincide well with those where the electrical conductivity of AIN and ZrB₂, respectively, begins to increase with increasing temperature. Therefore, it is considered that the polarization of the ceramics may take place and assist the migration, and consequently segregation, of reactive metals in braze alloys to the braze-ceramic interface during brazing.     

Abrasive wear of dental composite resins

Abrasive wear is a major problem in the application of dental composite resins. In this study the friction and wear behaviours of two types of dental composites: one containing relatively coarse filler particles and some microfillers (Estilux) and another containing only microfiller particles (Durafill), have been investigated by using a scratch testing machine. Experimental results show that the coefficients of friction in both composites are essentially constant for applied loads up to 20 N. The wear resistance of Durafill is better than Estilux. Under the same testing conditions, the size, shape and distribution of the filler particles are more important variables than applied load and sliding speed in controlling the wear mechanism. It is shown that for Estilux, plastic ploughing by the diamond indenter is the predominant mechanism. For Durafill, however, the formation and propagation of tensile cracks on the worn surface is the main wear mechanism. The effects of two different indenters, diamond and enamel, on the basic wear mechanisms are also discussed.     

In situ SEM studies on the effects of particulate reinforcement on fatigue crack growth mechanism of aluminium-based metal-matrix composite

The effects of particulate reinforcement on the fatigue behaviour and fatigue mechanisms of two 6061 aluminium-based metal-matrix composites (MMCs) in three different heattreatment conditions were studied in situ with a scanning electron microscope and compared to the unreinforced alloy in the as-received condition. It was observed that the fatigue properties of the MMCs were influenced by the ceramic particles in two ways: firstly the particles increased the fatigue stress intensity threshold mainly by crack-deflection and crack-closure mechanisms, and secondly, the particles raised the fatigue crack growth rates in the Paris region by providing an easy crack path. The effect of ageing was small on the fatigue stress intensity threshold of MMCs, but for the peak-aged MMCs the fatigue crack growth rates in the Paris region were faster. The mechanism of fatigue crack growth was largely associated with the matrix/particle interface and the linkage with subcracks initiated ahead of the main crack at high applied stress intensity factors.     

单模光纤中模耦合微扰功率谱与偏振关系的研究

提出用测量光纤偏振耦合率来确定模耦合系数，从而得到耦合微扰功率谱与双折射关系。它给出了光纤拉制中微扰作用 的信息，是研制偏振光纤的一种有效方法。