基于双磁介质层复合的超材料低频吸波体研究

本研究将磁性吸波涂层融入至超材料的结构设计中,得到了一种新型低频复合超材料吸波体,吸波体由环形电阻膜、双层磁性吸波涂层和金属背板组成。采用CST仿真软件计算了超材料吸波体的吸收性能,研究了吸波体各个结构参数对吸收性能的影响。仿真结果表明,设计的超材料吸波体厚度为2.5 mm时,在1.9和4 GHz处存在2个吸收峰,在1.59～6.59GHz频率范围内反射损耗低于-8dB,吸收带宽达到5GHz。通过吸波体电磁场分布对吸波机理进行了讨论。结果表明,吸波体低频吸收带宽的增加是由于表面的电阻膜图案改变了超材料吸波体的电场分布和磁场分布,促进了磁介质层的损耗。最后制备了吸波体样品并进行了反射率测试,实物测试结果与仿真结果基本一致,说明设计制备的吸波体具有优异的低频吸波性能,吸波带宽相比磁性吸波涂层大幅提高。     

Gradientenbetontechnologie

The technology of graded concrete – From the development of concrete mixtures and the conceptual design to the automatized manufacturing In accordance with the principle form follows force, the DFG Priority Programme (SPP) 1542 – Leicht Bauen mit Beton – focuses on energy efficient building elements which are designed specifically for desired operational demands. This concept is a specific adaption of the component's inner structure and works in parallel to the optimization of its outer shape which is often limited due to the outer geometry of slabs, walls and supporting pillars. The technology of graded concrete provides an innovative possibility to adapt the inner structure of a concrete component in order to meet defined static and structural‐physical requirements. The challenging demands imposed by the technology of graded concrete require a holistic approach including the development of the concrete mixtures, the design of the building components and finally the automatized manufacturing. In collaboration between the departments ILEK, IWB and ISYS of the University of Stuttgart a complete process chain for the manufacturing of functionally graded concrete components was realized. This approach for concrete results in fully recyclable building elements with significant savings in mass and energy.     

正交异性钢桥面板结构体系的疲劳破坏模式和抗力评估

正交异性钢桥面板的疲劳问题属于包含多疲劳破坏模式的结构体系疲劳问题。基于这一本质特性,以典型的正交异性钢桥面板结构体系为研究对象,由结构体系的主导疲劳破坏模式出发,提出正交异性钢桥面板结构体系疲劳抗力评估的新方法。以纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节为主要研究对象,设计8个足尺节段模型,主要包括传统纵肋与顶板焊接细节、新型镦边纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节,通过模型试验研究了两类重要构造细节的主导疲劳破坏模式和实际疲劳抗力,在此基础上结合切口应力评估方法探讨正交异性钢桥面板构造细节切口应力S-N曲线方程、结构体系的主导疲劳破坏模式等关键问题。研究结果表明：传统纵肋与顶板焊接细节和新型镦边纵肋与顶板焊接细节的主导疲劳破坏模式均为疲劳裂纹萌生于焊根并沿顶板厚度方向扩展,二者的实际疲劳抗力基本相同;纵肋与横隔板交叉构造细节的疲劳破坏模式为焊趾开裂沿纵肋腹板方向扩展;对于研究对象而言,萌生于纵肋与顶板焊接细节焊根并沿顶板厚度方向扩展的疲劳破坏模式为控制结构体系疲劳抗力的主导疲劳破坏模式。     

Unique Crystal Structure of a Novel Surfactant Protein from the Foam Nest of the Frog Leptodactylus vastus

Breeding by releasing eggs into stable biofoams (“foam nests”) is a peculiar reproduction mode within anurans, fish, and tunicates; not much is known regarding the biochemistry or molecular mechanisms involved. Lv‐ranaspumin (Lv‐RSN‐1) is the predominant protein from the foam nest of the frog Leptodactylus vastus. This protein shows natural surfactant activity, which is assumed to be crucial for stabilizing foam nests. We elucidated the amino acid sequence of Lv‐RSN‐1 by de novo sequencing with mass‐spectrometry and determined the high‐resolution X‐ray structure of the protein. It has a unique fold mainly composed of a bundle of 11 α‐helices and two small antiparallel β‐strands. Lv‐RSN‐1 has a surface rich in hydrophilic residues and a lipophilic cavity in the region of the antiparallel β‐sheet. It possesses intrinsic surface‐active properties, reducing the surface tension of water from 73 to 61 mN m^?1 (15 μg mL^?1). Lv‐RSN‐1 belongs to a new class of surfactants proteins for which little has been reported regarding structure or function.     

管输含蜡原油降凝技术研究进展

输送含蜡原油一直我国原油管输所面临的主要技术问题,一方面要保障含蜡原油的顺畅输送,另一方面还要考虑节能、安全等问题。对国内外原油降凝剂技术的发展概况和降凝剂的作用机理和类型进行归纳总结以及列举现场实例。另外,针对凝剂技术目前存在的问题和降凝剂技术发展趋势进行了分析。     

20英尺低温液体罐式集装箱的结构强度计算

根据《集装箱检验规范》(中国船级社)和IMDG CODE《国际海运危险货物规则》中的有关要求,进行了20英尺低温液体罐式集装箱的结构强度计算,分析时选取了板壳单元和梁单元,4个箱角刚性固定,将各个运动方向上的惯性力转化为动压力叠加到设计压力上,分别进行计算,计算结果满足规范要求。     

阻燃ABS树脂的发展现状与未来展望

首先对ABS树脂的性质、现状和阻燃的重要性进行了简要介绍。之后分别对溴系、磷系和无机金属化合物等阻燃剂在丙烯腈—丁二烯—苯乙烯三元共聚物(ABS)树脂中的应用现状及存在的问题进行了阐述,最后对今后阻燃ABS树脂的发展趋势进行了简单的分析和预测。