Multifunctional heteroatom zeolites: construction and applications

Multifunctional heteroatom zeolites have drawn broad attentions due to the possible synergistic effects in the catalytic reactions. Remarkable achievements have been made on the synthesis, characterization and catalytic applications of multifunctional heteroatom zeolite, while a review on this important topic is still missing. Herein, current research status of multifunctional heteroatom zeolites is briefly summarized, aiming to boost further researches. First, the synthesis strategies toward heteroatom zeolites are introduced, including the direct synthesis and postsynthesis routes; then, the spectroscopic techniques to identify the existing states of heteroatom sites and the corresponding physiochemical properties are shown and compared; finally, the catalytic applications of multifunctional heteroatom zeolites in various chemical reactions, especially in one-step tandem reactions, are discussed.     

衣架式机头口模设计公式的修正探讨

基于表征值方法和熔体等压线平行于模唇这一流动模型,对衣架式机头口模进行了流动分析,并发现了文献[1]提出的口模设计公式中的一个缺陷,即计算的扇形狭缝区域与歧管发生了分离,针对该缺陷给出了修正公式。     

基于神经网络和过程机理的热流体系统仿真

构建了一种基于复合神经网络和过程机理特性的热流体系统仿真模型 .该模型在形式上为一种复合人工神经网络模型 ,保证了模型具有十分理想的仿真速度 ;在网络模型设计上较好地考虑了系统输入与输出间的物理基础 ,网络模型在一定程度上由常规的黑箱模型转化为“灰箱模型” ,网络的训练除了具有常规的输入、输出间的纯数值映射关系学习功能之外较好地体现了对象输入与输出间的物理机理学习 ,保证了网络模型具有良好的联想能力、外推能力和时间递推能力 .     

水平矩形管内气液两相流界面波特性

<正>气液两相流中界面波的存在对传热、传质、阻力特性及稳定性都有很大影响。前人有关界面波的研究大多偏重于两相流中界面波的类型及其转变,而对其特征参数变化规律(如振幅、波长、频率和速度等)的研究则很少。但界面波对气液两相流流动阻力和流动结构影响机理的深入研究必须以了解界面波的各特性参数为前提,同时界面波有关特性参数的深入研究也可为气液两相流的数学理论化提供实验基础。 本文以气、水为工质,系统研究了水平矩形管内气液两相流的界面波特性。根据界面波在时域、幅域内的不同特征区别出了各种类型的波并给出了相应的波形和流型图。着重研究了界面波各特征量随气液两相流量变化的变化规律。     

铝阳极氧化膜孔内电沉积银及其抗菌性能

Aluminum specimens were anodized in a sulfuric acid bath, then silver was electrodeposited in pores of the anodized aluminum by using alternating current . The anodized aluminum with deposited silver was testedfor its antibacterial performance. The results show that the antibacterial rates of the specimens are above 95% against the growth of E. coil, P. aeruginasa, S. faecalis and S. aurens. The morphology of the silver in pores of anodized aluminum is characterized by transmission electron microscopy, and the micrographs indicate that silver is assembled in the form of nanowires with a diameter of 10 nm or 25 nm. The nanowires have a structure of parallel bright stripes alternating with parallel dark stripes.     

引入动态内存分析的微信撤回消息恢复方法

作为广受用户青睐的即时通信系统,微信在给人们生活带来极大便利的同时,也给不法分子提供了违法犯罪的新手段、新工具。微信聊天记录作为我国法律中明确列出的电子证据类型,其有效性引起广泛关注,使得微信聊天记录的恢复成为相关领域的研究热点。针对现有的聊天记录恢复研究多集中于删除消息的恢复,撤回消息的恢复尚未取得有效进展,通过研究PC版微信运行过程中的动态内存管理机制,分析撤回消息在动态内存中的特征字符及字段结构,对比文本、表情、图片等不同类型的消息在内存中的存储原理,提出一种基于动态内存分析的微信撤回消息恢复方法。利用Python语言编写的工具实现了对微信撤回消息原文、撤回状态、撤回方微信ID等内容的批量恢复,验证了该方法的有效性。     

Numerical simulation of small section rectangular tube in parallel welding

The welding temperature field and deformation of parallel arrangement small-section rectangular tubes is calculated by using a non-contact model. After comparing the computed results with the experimentally measured results, it shows that there exist big errors when applying this model to the numerical simulation of small-section rectangular tube＇ s welding temperature field and deformation. Based on a simple analysis of the errors, a contact model is presented. The heat transfer and stress analysis between small-section rectangular tubes and clamping fixture are simulated by using direct constraints method, and then the laws of the temperature distribution, which coincide with experiment, are obtained. A further numerical analysis of the stress and deformation are made, it shows that a ＂T＂ shaped stress-field is formed in the vicinity of the weld. As the stress-field departs from the centroid of tubes＇, this leads to the small rectangular tubes not only have a longitudinal deflection, but also have a transverse bending and deformation.     

添加剂对Al2O3／BN可加工陶瓷性能的影响

采用Si3N4和SiC作为Al2O3／BN可加工陶瓷的添加剂，考察了添加剂种类和含量对材料力学性能及可加工性能的影响。研究表明，2种添加剂均对调节体系中由于热膨胀失配所引起的人的内应力起到积极的作用。材料的抗弯曲强度随添加剂含量的增加而提高，同时可加工性能略有降低。尤其是Si3N4的加入使体系在热压烧结过程中原位反应生成液相x-Sialon，显著降低了烧结温度，促进材料的致密化。