柔性管接头焊接工艺及质量检验

柔性管接头是柔性钻具组合的重要环节，接头焊接工艺的选择直接影响到焊缝的强度。论述了对４０ＣｒＭｎＭｏ合金钢柔性管坯料所进行的取样分析，并介绍了所采用的焊接设备和焊丝的选用、待焊接头的结构、焊接准备及焊接工艺过程等，指出合理地选择焊接工艺参数能避免柔性管接头在焊接过程中产生缺陷，并且焊后具有良好的综合机械性能，符合柔性钻具组合的强度设计要求。对焊接试样的金相分析和对柔性管短节试样的Ｘ射线探伤检验表明，采用半自动熔化极氩弧焊焊接工艺能够满足焊接性能要求。     

中国的量子化霍尔电阻标准

1988年10月举行的国际计量委员会(CIPM)第77次会议决定,从1990年1月1日起在世界范围内启用量子化霍尔电阻标准。中国计量科学研究院从1987年起也开始了建立量子化霍尔电阻标准的研究课题,该项标准现已建成,用量子化霍尔效应复现的10kΩ和1kΩ电阻量值的不确定度为2.2×10~(-8)。     

红曲菌Monacolin K合成基因的研究进展

聚酮化合物Monacolin K是一种高效的降胆固醇药物,由红曲菌和土曲霉次级代谢产生。早期以土曲霉为研究对象,揭示了相关的生物合成基因簇及其功能。近年来的研究发现,虽然Monacolin K在这2种产生菌中的生物合成途径完全相同,但红曲菌中Monacolin K相关的生物合成基因和土曲霉并不完全一致。对红曲菌功能基因组的深入研究,以及相应遗传转化体系的建立与完善,对进一步开发生产更多的聚酮化合物必将出现新的契机。     

外墙外保温工程现场拉拔试验

介绍了在保温板材与基层的粘结强度现场拉拔试验中粘结剂的选用。     

生物柴油对柴油机油氧化、清净和抗磨性能的影响

在柴油机油中分别加入不同比例的生物柴油和矿物柴油,通过实验室模拟实验,研究了生物柴油和矿物柴油对柴油机油氧化安定性、高温清净性及抗磨性能的影响.结果表明,与矿物柴油相比,生物柴油自身较易氧化,并且明显加速了基础油和柴油机油的高温氧化变质,使得柴油机油的氧化安定性、高温清净性及抗磨性能变差.     

硫化蓖麻油润滑添加剂在菜籽油基础油中的摩擦学性能

在蓖麻油分子中引入硫,合成了一种新型环境友好润滑添加剂（SCO）,并利用红外光谱对其主要官能团进行了表征。通过四球试验机考察了SCO在菜籽油中的抗磨性能与极压性能,用X射线光电子能谱仪对其磨痕表面元素进行分析,探讨该类添加剂的极压抗磨作用机理。结果表明,硫化蓖麻油润滑添加剂在菜籽油中具有优良的极压抗磨和减摩性能,其润滑作用机理是由于长链蓖麻油分子的载体作用、硫的高反应活性以及二者的协同作用与摩擦金属表面形成了一层高强度的吸附膜和（或）摩擦化学反应膜。     

Aliphatic Amidediol and Glycerol as a Mixed Plasticizer for the Preparation of Thermoplastic Starch

The synthesis of 2‐hydroxy‐N‐[2‐(2‐hydroxy‐propionylamino)‐ethyl]propionamide (“aliphatic amidediol”) is described. Aliphatic amidediol and glycerol were used as a novel mixed plasticizer for corn starch to prepare thermoplastic starch. Fourier transform infrared (FT‐IR) spectroscopy proved that the mixture of aliphatic amidediol and glycerol could form more stable and strong hydrogen bonds with starch molecules than glycerol alone. By scanning electron microscopy (SEM) and X‐ray diffraction (XRD) it was proven that native starch granules and crystalline structures were broken and starch was plasticized. Tensile testing revealed that TPS plasticized by aliphatic amidediol and glycerol (AGPTPS) showed a better mechanical properties than TPS plasticized by glycerol (GPTPS). Furthermore, the water resistance of AGPTPS was better than that of GPTPS. In addition, dynamic mechanical thermal analysis (DMTA) showed that both storage modulus and glass transition temperature (T_g) of AGPTPS were higher than those of GPTPS.     

Experimental and numerical studies of stress/strain characteristics in riveted aircraft lap joints

The fatigue property of riveted lap joint is greatly related to the riveting-induced residual stress, especially the stress distribution on the faying surface. However, an accurate study of the residual stress characteristics in the riveted sheet could be very difficult. In this paper, both numerical and experimental investigations were carried out on the stress/strain characteristics in riveted aircraft lap joints. A special specimen was designed for the test of strain variations on the faying surface of the sheet by microstrain gages. For the numerical simulation, the rivet squeezing process was analyzed using the explicit dynamic finite element (FE) method, whilst a general static FE analysis was employed for the elastic springback after the squeeze force was removed. A comparison of the strain variations between the experimental results and FE simulations shows a general good agreement, although there may be some difference for points measured near the hole surface. The FE analysis reveals that both compressive and tensile residual stresses could be introduced in the riveted sheet. Massive compressive residual stress can be created in the near-surface layer of the hole. However, the stress level is not always increased with increasing the squeeze force, and so is the improvement of fatigue life observed. Further study is still necessary to account for the fatigue life decreasing effect caused by a high squeeze force.

     

基于图像色网点化设计的织物结构呈色特征

为克服提花织物色彩仿真设计受影光组织库显色规律制约的问题,提出一种图像色的网点化设计方法。采用3种网点大小与4种排列角度对黑白渐变色阶进行网点化设计,织造织物样品;并将网点织物样品组与一组采用缎纹影光组织库的织物样品进行比较研究。通过对织物样品的比较分析表明:网点越大则黑白渐变色织物样品组的明度值变化越均匀,但不足之处是在实践应用中对原始图像的细节表现减少;在网点排列角度方面,采用15°和75°角具有更稳定的织物交织结构;网点织物样品组的明度差离散平均值较后者降低了31.94%,表明了图像色的网点化设计使织物具有更好的呈色均匀性。     

基于弧形电容器的浆纱回潮率在线测量

为提高上浆质量以及解决使用接触式电阻含水率测量仪会破坏浆膜的问题,设计开发了基于弧形电容器的浆纱回潮率在线测量系统。根据浆纱在弧形电容器中的电场模型和电容法测量原理,利用指数回归算法建立电容差与回潮率的函数模型。上浆时,浆纱穿过弧形电容器,电感、电容、电阻(LCR)电桥测试仪将测量的电容值数据传到上位机,上位机根据模型计算出实时浆纱回潮率。讨论了弧形电容器结构、LCR电桥测试仪测试参数、环境温湿度、浆液含固率、浆纱线密度、回潮率对测量电容值的影响。实验结果表明：电容值受LCR电桥测试仪测试频率的影响较大;电容值随电容器结构参数极板长度、极板包角的增大而增大,与极板曲率半径呈负相关;环境温湿度会对电容值产生复杂影响,因此要求在恒温恒湿条件下进行测量;浆纱回潮率对电容值的影响显著,且回潮率与电容差呈指数函数关系。在上浆机上使用电容式回潮率在线检测系统进行测试,得到的浆纱回潮率与烘箱法测量结果相比平均误差小于5%,本文系统具有一定的工程实用价值。