Rhizobium trifolii capsular polysaccharide: a novel biopolymer with striking physical properties

The physical properties of the capsular polysaccharide of Rhizobium Trifolii (CPS) were investigated. Viscosity measurements provided information about the hydrodynamic volume of single coils, the perturbation of solvent flow and the shear-thinning behaviour of concentrated solutions. Changes in chain geometry and the development of an intermolecular network as a function of temperature were monitored using the techniques of optical rotation and dynamic oscillation. Finally, analysis of calorimetric thermograms elucidated the type of interactions between CPS and the bacterial levan. Overall, the Rhizobium polysaccharide was found to form thermally-reversible gels at an extremely low 'minimum critical gelling concentration' (c_o∼ 0.35gl^-1). At temperatures above the gel melting point (∼ 48°C), however, the compact polymer coils entangled at comparatively high concentrations (about 60 times higher than c_o). In the presence of a highly branched levan, the thermal stability of ordered CPS structures increased as a consequence of thermodynamic incompatibility between the two polymers.     

化学防水材料的应用与发展

本文综合阐述了化学防水材料的起源、应用范围、种类及发展趋势。     

Application of electromagnetic-assisted stamping (EMAS) technique in incremental sheet metal forming

The application of high velocity electromagnetic-assisted stamping (EMAS) technique in incremental sheet metal forming has been proposed. EMAS whose principle is based on Lorenz force is a hybrid forming process that uses both quasi-static conventional stamping technique and electromagnetic forming actuators built into sharp corners and other difficult-to-form contours to form metals. The recent push to use more artificial intelligent (AI) aluminum alloys in automobile and aircraft industries as a result of increasing demand for fuel efficient cars and aircrafts, large size vehicle panels, improved formability limit of materials and weight reduction have placed EMAS as one of the best high velocity forming technique.It is believed that the end result of this vision will lead to more cost effective land and aerospace vehicles.     

新型线圈发射器的电磁场仿真分析

电磁发射拥有许多化学发射不可比拟的优点,近年来受到各国的广泛关注。传统发射器需在线圈内部加装位置传感器,这使得线圈磁场分布不均且结构复杂。该文基于电磁感应原理,设计出了新型线圈发射器模型,该模型利用线圈外部的传感器来控制电路放电时间,克服了传统结构的缺陷。借助SIMPLORER和Maxwell仿真软件对发射器的主体电路和线圈磁场进行分析,得到了磁场中弹丸的静态和动态特性曲线。仿真结果验证了该新型发射器的作用机理,并得到了四级发射器模型的结构参数。该新型发射器可把30g弹丸加速到12.00m/s。结果表明该新型发射器结构简单、线圈内部磁场分布均匀,大大提高了模型的发射效率和系统的稳定性。     

托盘循环式钢卷运输系统设备技术

介绍了一种托盘循环式钢卷运输系统设备技术,即通过钢卷托盘在辊道上循环运转来实现钢卷输送,应用于冷连轧、热连轧的钢卷运输线。     

"不良"结霜现象的分析和对策

空气冷却盘管在冷库制冷过程中结霜是经常发生且不可避免的问题,必须要周期性的除霜.在温湿图上,如果空气降温处理过程穿越了饱和线,就可能发生"不良"结霜的问题."不良"结霜是一种低密度、蓬松的、雪状霜,与其他结霜的类型相比,"不良"结霜会更快地减少空气流通面积,盘管换热能力迅速下降.通过分析其形成原理,提出了相应的防止措施,能有效的减少"不良"结霜.     

利用罗果夫斯基线圈测量静电放电电流

分析了测量静电放电电流时Rogowski Coil的工作原理，并给出了其结构和电气参数的估算方法。通过试验验证了Rogowski Coil测量静电放电电流的可行性。同时还提出了利用屏蔽盒来避免外磁场对测量线圈干扰的方法，并对屏蔽盒设计的关键问题作了进一步的探讨。     

24kV级汽轮发电机绝缘技术研究

介绍对24kV级汽轮发电机及线圈的绝缘材料和结构的研究，及其研究成果根据实际进行部分应用的情况。图2表5     

绕花丝管内插物对蒸汽——空气混合物系凝结换热性能的影响

对蒸汽在竖直管内的凝结换热进行了实验研究。实验表明，含有不凝性气体（空气时，蒸汽在光管内的凝结换热性能显著下降，而当蒸汽流速增大时，下降程度减小，进一步证实了现有的理论结果。特别是，实验发现，当管内插入大空隙率花丝元件时，能显著改善不凝性气体对蒸汽凝结换热的不利影响。此结果将对非共沸制冷工质的广泛使用产生深远影响。     

304不锈钢冷轧卷连续钝化工艺参数的正交试验

用CIE1976L^*a^*b^*色空间中的白度HW^*作为不锈钢冷轧卷钝化后表面质量的评价指标，对304(18-8)奥氏体不锈钢板材的钝化工艺参数(HNO3 10％～20％，HF 0．8％～2．5％、钝化温度40～70℃、钝化时间1．0～3．0min)进行了正交试验和方差分析。试验和分析结果得出，不同炉批304不锈钢冷轧卷材，因成分和工艺差异，使板材最佳钝化工艺参数稍有不同，但从整体来看，304不锈钢卷材钝化的最佳工艺参数为：HNO3 10％～12％，HF 2．0％～2．5％，钝化温度40～50℃，钝化时间2．0～2．5min。