催化裂化汽油降烯烃技术研究进展

从FCC技术、醚化改质技术、芳构化改质技术等方面介绍了催化裂化汽油降烯烃技术的发展状况。对FCC自身进行改造的方法简单易行;轻汽油醚化和芳构化改质技术不仅降低了汽油的烯烃含量,同时可以大大提高汽油的辛烷值,但汽油中醚类及芳烃的含量都有一定的限制。目前要降低汽油烯烃含量,需要发展一整套综合技术或措施,然而要从根本上解决问题,必须对汽油的生产结构进行调整,降低催化裂化汽油的比重,增加烷基化、异构化、芳构化、重整等汽油的比例。     

Paint Solvent Permeation Resistance of Polyethylene,Polyethylene/Polyamide and Polyethylene/Modified Polyamide Bottles

The main objective of this study is to investigate the barrier mechanisms and properties of polyethylene, polyethylene (PE)/polyamide (PA) and polyethylene/modified polyamide (MPA) bottles against paint solvent permeation. In addition to the paint mixed solvent, the barrier properties of these bottles against the permeation of pure main solvents contained in the paint mixed solvent were investigated to understand the permeation mechanisms of the paint solvents. The paint solvent permeation resistance improves dramatically after blending PA and MPA barrier resins in PE matrices during blow‐molding. In fact, by using proper compositions, the white spirit permeation rates of PE/MPA and PE/PA bottles at 40°C are about 360 and 50 times slower than that of the PE bottle, respectively. Further investigations showed that, after blending the MPA and PA barrier resins in PE matrices, the hydrocarbon solvents present in the white spirit were nearly blocked without permeation during the permeation tests, i. e., PE/MPA bottles inhibited the permeation of hydrocarbon solvents more successfully than PE/PA bottles. In contrast, the rates of polar solvents with ketone, ether and alcohol functional groups permeating through the PE bottles are much slower than that of the white spirit and only slightly faster than those through the PE/PA and PE/MPA bottles. On the other hand, the paint mixed solvent permeation rates of PE bottles are approximately equal to the summation of permeation rates of the solvents present in mixed solvents calculated using a simple mixing rule. Somewhat surprising, the permeation rates of mixed solvents of PE/MPA bottles are dramatically faster than those calculated using a simple mixing rule, when the polar solvent contents are in a certain range.     

Interfacial interactions in calcium carbonate–polypropylene composites. 2: Effect of compounding on the dispersion and the impact properties of surface-modified composites

This study was carried out to investigate the influences of compounding process and surface treatment on calcium carbonate (CaCO₃) filled polypropylene. The compounding process is discussed with reference to a twin-screw extruder and an internal mixer. The calcium carbonate filler was surface-treated with a liquid titanate coupling agent (LICA 12) and stearic acid. Composites of different weight fractions were prepared by both compounding processes, and their impact properties were evaluated. The notched Izod impact strength increased with CaCO₃ content up to a maximum at about 10 vol%, and then decreased. Surface treatment of CaCO₃ filler generally yielded composites of higher impact strength than untreated system. Though LICA 12 was more effective than stearic acid in modifying the filler, the low-cost stearic acid proved to be more effective when dealing with the impact properties of composites. Moreover, the composites from a Brabender Plasti-corder exhibited better gross uniformity than that from the twin-screw extruder. However, good filler dispersion and uniform microscopic morphology, as revealed by SEM microscopy, was observed in the samples from the twin-screw extruder. Polym. Compos. 25:451–460, 2004. © 2004 Society of Plastics Engineers.     

新现代主义建筑论(上)

主要论述了新现代主义建筑的理论基础,内涵,美学特征及其对当代建筑实践的启示意义。     

Hybrid Genetic Algorithms for Optimization of Truss Structures

The genetic algorithm (GA) is a new optimization paradigm that models a natural evolution mechanism. The framework of the GA naturally corresponds to a discrete optimization problem. Although the GA is very robust, it is also very computationally intensive and hence slower than other methods. To speed up the convergence, this article proposes a hybrid GA that combines the concept of survival of the fittest with the concept of adaptation. The fully stressed design optimality criterion is employed to play the role of adaptation. Numerical examples show that even though the displacement constraints are active, (1) both average weight and minimum weight obtained by a hybrid GA are less than those obtained by a pure GA, (2) a hybrid GA is more stable than a pure GA, and (3) the speed of convergence of a hybrid GA is superior to that of a pure GA.     

Optimization and Neural Network in New Product Development

New product introduction is vital to a firm's growth and prosperity. A company needs to develop a process to determine how to find and develop new product ideas and finally, how to successfully introduce them into the marketplace. To address this problem, this study proposes a new approach that combines neural network, analytic hierarchy process (AHP) and linear programming (LP). A neural network is used to classify the feasibility of ideas/projects in new product development and the theory of AHP is applied to evaluate the interdependence among projects. A linear programming model is then developed and used to allocate the limited financial resources of the firm to the competing projects.     

钨合金破片对屏蔽装药撞击起爆的实验研究

分别为93钨和钨锆合金破片撞击仿真战斗部装药－覆盖金属盖板的注装B炸药（屏蔽装药）,采用“升－降”法研究了装药的起爆（引燃）临界性,分析了两种破片撞击作用下的装药起爆（引燃）的机理,研究结果表明,钨锆合金破片具有更强的起爆（引燃）战斗部装药的能力;93钨破片对其起爆（引燃）主要是冲击波作用的结果,而钨锆合金破片则主要是机械作用的结果。     

指令制导防空导弹全弹道 飞行仿真系统研究

对指令制导防空导弹全弹道飞行仿真进行了研究,建立了指令制导防空导弹全弹道飞行仿真系统,详细描述了该系统的组成及功能,为防空导弹训练、维修模拟器材的研制提供了实验基础。     

Influence of Assembly Parameters on Tensile Behavior of Hybrid CMC and Superalloy Bolted Joints by Progressive Damage Analysis

基于渐进损伤分析的装配参数对陶瓷基复合材料与高温合金

混合螺栓连接结构拉伸行为的影响

吕超¹,李锋¹,赵淑媛²,孙茜³,李明瑞²,孙新杨⁴

（1.中国航天空气动力技术研究院,北京 100074;2.哈尔滨工业大学 特种环境复合材料技术国家级重点实验室,哈尔滨 150080;3.中航工业集团公司沈阳飞机设计研究所,沈阳 110000;4.哈尔滨工业大学 航天学院,哈尔滨 150001）

创新点说明：

采用ABAQUS有限元软件对陶瓷基复合材料和高温合金螺栓连接结构进行了渐进损伤分析,研究了连接结构装配参数对混合连接结构拉伸性能的影响规律,并讨论了连接结构的损伤失效模式,为提高陶瓷基复合材料连接结构的结构效率及服役安全性提供理论基础。

研究目的：

在飞行器结构应用中,陶瓷基复合材料与金属螺栓连接件的强度分析与结构设计对提高结构承载效率及维护结构完整性起着至关重要的作用,研究连接结构装配参数对陶瓷基复合材料-高温合金螺栓连接结构拉伸性能的影响,对其在航空航天领域的运用具有重要意义。

研究方法：

采用有限元软件ABAQUS建立了2D编织C/SiC陶瓷基复合材料与高温合金GH4169组成的单钉单搭接螺栓连接结构的有限元分析模型,结合Fortran语言将非线性本构模型、失效准则及材料退化模型编写成用户子程序UMAT文件,并嵌入到ABAQUS有限元软件中实现高温拉伸条件下陶瓷基复合材料与高温合金沉头螺栓紧固件的渐进损伤分析。基于此模型研究了连接结构装配参数对混合连接结构拉伸性能的影响规律,并讨论了连接结构的损伤失效模式。

结果：

2D编织C/SiC复合材料与高温合金组成的螺栓连接结构施加适当的预紧力可以提高连接结构的刚度和强度,但过大的预紧力会使复合材料板厚度方向发生破坏,从而导致接头强度下降。钉孔间隙的增加将加剧孔内挤压区域的应力集中现象,导致结构强度降低。

结论：

本研究针对陶瓷基复合材料和高温合金螺栓连接结构,研究了连接结构装配参数对混合连接结构拉伸性能的影响规律及相关失效模式,为陶瓷基复合材料连接件的结构设计和工程化应用提供了技术支撑。

关键词：陶瓷基复合材料;渐进损伤分析;拉伸性能;预紧力;钉孔间隙

     

BaMg2-x（PO4）2：xEu^3＋橙红色荧光粉的制备及发光性质

采用高温固相法合成BaMg2–x（PO4）2：xEu^3＋橙红色光致荧光粉。研究了激活剂Eu^3＋掺量及电荷补偿剂对其发光性质的影响。X射线衍射显示样品为纯相BaMg2（PO4）2晶体结构。光致光谱表明,该样品适于UV–LED（ultraviolet–light emitting diode）管芯（350～410 nm...