Fluid catalytic cracking technology: current status and recent discoveries on catalyst contamination

The fluid catalytic cracking (FCC) technology is one of the pillars of the modern petroleum industry which converts the crude oil fractions into many commodity fuels and platform chemicals, such as gasoline. Although the FCC field is quite mature, the research scope is still enormous due to changing FCC feedstock, gradual shifts in market demands and evolved unit operations. In this review, we have described the current status of FCC technology, such as variation in the present day feedstocks and catalysts, and particularly, great attention is paid to the effects of various contaminants of the FCC catalysts of which the latter part has not been sufficiently documented and analyzed in the literature yet. Deposition of various contaminants on cracking catalyst during FCC process, including metals, sulfur, nitrogen and coke originated from feedstocks or generated during FCC reaction constitutes a source of concern to the petroleum refiners from both economic and technological perspectives. It causes not only undesirable effects on the catalysts themselves, but also reduction in catalytic activity and changes in product distribution of the FCC reactions, translating into economic losses. The metal contaminants (vanadium (V), nickel (Ni), iron (Fe) and sodium (Na)) have the most adverse effects that can seriously influence the catalyst structure and performance. Although nitrogen and sulfur are considered less harmful compared to the metal contaminants, it is shown that pore blockage by the coking effect of sulfur and acid sites neutralization by nitrogen are serious problems too. Most recent studies on the deactivation of FCC catalysts at single particle level have provided an in-depth understanding of the deactivation mechanisms. This work will provide the readers with a comprehensive understanding of the current status, related problems and most recent progress made in the FCC technology, and also will deepen insights into the catalyst deactivation mechanisms caused by contaminants and the possible technical approaches to controlling catalyst deactivation problems.     

8Mbps数字电视编解码器系统

本文出了８Ｍｂｐｓ数字电视编解码器的硬件实现方案，包括视频、音频信道三个部分，同时给出了样机的测试结果，最后略地介绍了此编解码器的应用情况。     

C50引导功能的使用

Ｃ５０内部具有９Ｋ单指令周期访问的片内ＲＡＭ，在应用程序不太大的情况下，将程序在运行前由存取速度较慢的片外的ＥＰＲＯＭ读入片内ＲＡＭ，再在零等待状态下运行不失为一种方便快速的方法。本文就此进行了说明。     

饲料与动物营养配方专家系统的设计与实现

本文介绍饲料与动物营养配方系统（ＦＡＮＰＥＳ）的实现方法，阐述了系统总体结构与功能特点，叙述了系统知识库、推理机制及智能化配智方程序设计的技术。     

含盐陶粒掺量对水泥混凝土力学性能的影响

为了探究含盐陶粒对骨料碎石的替代给混凝土力学性能带来的影响,给含盐陶粒混凝土的设计施工提供理论依据,试验通过对不同替代率各组试件的抗压试验、抗折试验及耐磨性试验研究分析,得出如下结论:1)含盐陶粒混凝土的抗压强度随陶粒对骨料碎石的替代率增大而减小,当替代率为100%时,强度下降幅度达39.3%;2)根据含盐陶粒混凝土界面破坏形态和机理,证实陶粒与水泥石的界面黏结力比普通集料和水泥石的界面黏结力大,陶粒本身强度决定了混凝土的强度;3)当含盐陶粒的替代率小于等于70%时,混凝土的抗折强度大于4 MPa,可以满足各交通量等级条件下的规范设计抗弯拉强度要求;4)含盐陶粒混凝土的磨耗值随着含盐陶粒的替代率增大而增大,当陶粒对骨料碎石的替代率达到100%时,混凝土的磨耗值增长幅度为67%,各组试件的磨耗值均小于规范3.6 kg/m~2的要求,证实了含盐陶粒混凝土能满足路面的耐磨性要求。     

基于风景园林信息模型(LIM)的山地 景观地形参数化设计实验研究——以 Civil 3D和InfraWorks交互设计为例

缺乏参数关联与控制的山地设计在科学性与精准性 上出现诸多设计障碍,如山地场地、道路等三维设计信息与二 维设计不匹配;山地曲线、曲面地形要素设计精度不高等。 借鉴BIM技术在建筑参数化设计中的应用,探索Civil 3D与 InfraWorks协同处理山地地形并进行信息交互的设计方法, 完成山地地形三维模型设计与二维设计的参数关联,从而优化 山地设计程序,提高山地设计精细化程度,并为设计者即时提 供设计反馈信息和设计变更途径。通过研究实现山地景观信息 在BIM平台中的集成应用,构建基于风景园林信息模型(LIM) 的山地设计路径,为山地地形设计提供参数化解决方案。     

环境成就地标建筑——以重庆大剧院与悉尼歌剧院为例

通过对城市地标建筑的发展及其一般形态的概述,引出城市地标建筑无论是在视觉层面还是经济文化层面都离不开与其周边环境肌理的契合,与城市自然风貌以及人造工程环境共同交互影响。以重庆大剧院与悉尼歌剧院为例,通过对其体量的大小,基地、立面、外部轮廓的塑造及其色彩的选择与其周围环境关系的对比,挖掘出重庆大剧院纵然具有地处关键、体量高大、造型新颖等特点,却因没把握好同城市环境肌理的契合而失去地标效应。指出在设计城市地标建筑时,应因地制宜,充分结合当地自然环境及其地域文脉,才能成就其"地标性",推动地标经济效益。     

Magnetic Fe3O4-Reduced Graphene Oxide Nanocomposites-Based Electrochemical Biosensing

Nano-Micro Letters - An electrochemical biosensing platform was developed based on glucose oxidase (GOx)/Fe3O4- reduced graphene oxide (Fe3O4-RGO) nanosheets loaded on the magnetic glassy carbon...     

±660 kV银东直流大截面导线耐张线夹断裂故障分析

耐张线夹是输电线路的关键连接部位之一,其压接质量和运行可靠性直接影响输电线路的稳定运行.通过外观尺寸检查、导线力学性能检测、X射线成像检测、解体分析、扫描电镜分析、能谱分析等方法,对±660 kV银东直流输电线路大截面导线耐张线夹断裂原因进行了原因分析,结果表明,耐张线夹铝绞线与钢锚之间无相对滑动,钢芯断裂的主要原因为...     

Research on social network influence maximization algorithm based on time sequential relationship

For the time sequential relationship between nodes in a dynamic social network,social network influence maximization based on time sequential relationship was proved.The problem was to find k nodes on a time sequential social network to maximize the spread of information.Firstly,the propagation probability between nodes was calculated by the improved degree estimation algorithm.Secondly,in order to solve the problem that WCM models based on static social networks could not be applied to time sequential social networks,an IWCM propagation model was proposed and based on this,a two-stage time sequential social network influence maximization algorithm was proposed.The algorithm used the time sequential heuristic phase and the time sequential greedy phase to select the candidate node with the largest influence estimated value inf (u) and the most influential seeds.At last,the efficiency and accuracy of the TIM algorithm were proved by experiments.In addition,the algorithm combines the advantages of the heuristic algorithm and the greedy algorithm,reducing the calculation range of the marginal revenue from all nodes in the network to the candidate nodes,and greatly shortens the running time of the program while ensuring accuracy.