提高发泡同轴电缆防潮性能的研究

根据特高频信号传输衰减原理进行衰减-吸潮性试验。重点讨论了发泡绝缘线芯上发泡质量对防潮性的影响,并对影响发泡质量的多种因素进行了分析,并提出了绝缘线芯的防潮措施。试验给出最佳发泡挤出工艺A2B2C2D2,所得发泡体泡孔细密、分布均匀、互相闭合不相通。据此发泡工艺和引述的三项防水防潮措施生产的同轴电缆,经288 h的湿热试验,其信号衰减增量都小于1%。     

Modification and properties of African yam bean (Sphenostylis stenocarpa Hochst. Ex A. Rich.) Harms starch I: Heat moisture treatments and annealing

African yam bean (Sphenostylis stenocarpa) starch was subjected to heat moisture treatments at 18% (HMT-18), 21% (HMT-21), 24% (HMT-24), 27% (HMT-27) and excess (Annealing) moisture levels. Proximate chemical composition of the starch samples revealed that the moisture content of the starches ranged between 6.7% and 12.5%. Following modification of the native starch, there was a reduction in the moisture level of the heat moisture treated starches from HMT-18 to HMT-27. However, the annealed starch (HMT-ANN) retained higher moisture content compared to native starch (AYB-Native). The carbohydrate, protein, ash, amylose and fat content reduced with all the forms of heat treatments. At the temperature range studied (60–90 °C), increasing level of heat moisture treatments reduced the solubility and swelling capacity. pH also exert a profound effect both on the solubility and the swelling of the starch. Increasing degree of alkalinity increased both solubility and swelling capacity. In the native and modified starch samples, replacement of the wheat flour by the starch resulted in increased alkaline water retention of the blends. Water absorption capacity of the starch increased with the severity of moisture treatments, while the oil absorption capacity decreased. Apart from HMT-18, there was improved gel forming capacity of all the other heat-modified starches.Pasting temperature increased after hydrothermal modifications, whereas peak viscosity (P_v), Hot Paste Viscosity (H_v), setback and breakdown values all reduced after heat moisture treatments. All the starches were of type-B viscosity.Differential scanning calorimetry studies revealed that heat moisture treatment shifted the onset temperature (T_o), peak temperature(T_p) and conclusion temperature (T_c) to higher values. The gelatinisation temperature of the annealed starch was comparable to native starch. In addition, gelatinisation band of the native starch increased progressively from HMT-18 to HMT-27. Heat moisture treatment reduced the gelatinsation enthalpy (ΔH), while the enthalpy of retrogradation(ΔH_r) increased with the storage time of the gelatinised starch. Retrogradation enthalpy of the heat moisture conditioned starches were lower than the value obtained for the native starch.X-ray diffraction studies of the starch indicated that all the starch samples showed the type-C diffraction pattern. Differences were however observed in their degree of crystallinity. Native starch exhibited the lowest crystallinity (20%) while annealed starch had the highest crystallinity (27%)Microscopy studies revealed surface indentation, formation of groves in the central region, folding of starch granules and formation of doughnut-like appearance in some of the starch samples.     

微波测量纤维含水率的方法

选择棉花、羊毛、腈纶纤维为试验材料,通过不断给纤维加湿以获得不同含水率的样品.利用自制的波导网络分析仪,研究不同纤维材料的含水率与电磁波的屏蔽效能和功率吸收率之间的关系.结果表明,纤维材料本身对电磁波的影响可以忽略不计.不同含水率的纺织材料对电磁波屏蔽效能的变化趋势符合指数规律;不同含水率的纺织材料对电磁波的功率吸收率与其含水率的变化符合线性规律.因此,在纤维贸易、加工等过程中,可通过使用微波仪器快速测量其屏蔽效能值来反映它们的含水率.     

重视高炉鼓风湿分的影响和调剂作用

介绍了高炉鼓风湿分的变化范围及对高炉操作的影响程度,强调必须重视该因素的影响。用湿分调节炉况的方法具有直接、快速、有效的特点,应当得到保留和使用。南方企业应设置鼓风脱湿设施。高炉鼓风湿分测量仪有效地解决了湿分的直接测量和湿分调节的准确计量问题。     

水分对煤矿许用膨化硝铵炸药抗爆燃性能影响的试验研究

根据抗爆燃性有关标准的测试方法,详细地测试和研究了水分和装药密度对受试的一级和二级煤矿许用膨化硝铵炸药的抗爆燃性的影响,同时测定了被发装药的残药量.试验说明煤矿许用膨化硝铵炸药具有良好的抗爆燃性,水分对抗爆燃性基本没有影响.     

树脂封装中湿气浸入和成形缺陷的研究

介绍了电子元件的封装技术.主要针对树脂封装进行研究,分析湿气浸入、成形缺陷及表现形式,并提出防止措施,以利于对我国的微型包装中的电子封装及微电子业有所促进.     

浅谈自动土壤水分监测网络通讯体系

江苏省自动土壤水分监测网络基于成熟的土壤水分测量技术和GPRS无线传输网络技术。该网络将省内位于不同地点的自动土壤水分观测仪通过无线通讯网络（GPRS）进行统一调度、监控和土壤水分数据的收集汇总,在很大程度上增强了对全省干旱、洪涝等灾害的预警能力,可以有效的为农业生产提供气象指导。     

六氟化硫气体中水分危害及微水测量要点

在以六氟化硫气体为灭弧介质的断路器和GIS设备气室中,六氟化硫气体含水量过多,将对设备运行及维护产生危害。给出了不同气室中六氟化硫气体含水量标准,介绍了含水量测量方法,分析了影响微水含量测量的几个因素,并提供了相应的应对措施,准确的测量结果,为设备的可靠运行打下了良好的基础。     

汽轮机湿汽损失的分析与研究

对某台抽汽凝汽式机组末级叶片的水蚀特征进行了分析,提出了利用原有准则计算湿汽损失是有缺陷的．指出湿汽损失应该由2个部分组成：一是来源于一次水滴损失,二是来源于二次水滴损失,并且当蒸汽湿度大于一定值时,二次水滴损失应该大于一次水滴损失．同时,阐述了有核凝结形成的一次水滴也会对叶片产生水蚀作用．通过使用汽轮机外缘内表面去湿隔板可以减小湿汽损失,提高机组效率,延长叶片使用寿命．     

Mechanical properties of pultruded glass fiber-reinforced plastic after moistening

The kinetics of moisture sorption under immersion in water at room and elevated temperatures and flexural characteristics of dry (conditionally initial) and wet (moistened up to saturation level) composite material were investigated on flat specimens of polyester based glass fiber-reinforced plastic, cut from I-beam pultruded profile. It was found that the coefficients of diffusion and swelling are different in three principal axis of the composite. The former have the largest value in fiber axis direction, but the latter – in transverse to fiber axis direction out of plane of the layers. The observed difference in kinetics of mass gain and change of volume strain for the specimens of various sizes allowed evaluate the volume of pores, filled with water. The large data spread for the specimens, cut from the flanges, was found. Edge specimens have lower density and showed lower elastic and strength characteristics. The material specimens moistened up to saturation level showed the decrease in flexural modulus and strength for 8% and 16.5%, respectively. No effect of sorbed moisture on tensile modulus and strength of the composite (tension along the fiber axis direction) was found.