Effect of Testing Conditions on Fibre-Bundle Tensile Properties Part Ⅱ: the Gauge Length and Elongation Speed in Wool Fibre Bundle Measurement

The testing conditions of a fibre bundle tensile tester (TENSOR) are elongation speed (ES), gauge length (GL), pretension, jaw pressure, environmental temperature and relative humidity, instrument linearity and sensitivity. The effects on fibre-bundle tensile properties at different GL and ES have been discussed in detail and compared with Peirce's theories on the weaklinks and the breaking time effect. The experimental results indicate that the tensile properties of fibre bundles are strongly affected by GL and vary with different GL. The reasonable GL should be 5-15mm rather than 3.2mm for wool bundle measurements. The ES ranging from 20mm/min to 40mm/min is beneficial for obtaining comparatively stable and accurate tensile values, whereas 20 mm/min used in current testing for wool fibre bundles is at the lower limit of the suggested range. For bundle modulus measurement, the sampling interval must be selected appropriately. The new calculation of the sampling interval has been established.     

具有无限长区域非线性奇摄动方程

用伸长变换和匹配条件讨论了一类具有无限长区域的非线性方程的摄动问题：y″ 2/xy′ εy^2y′=0,x∈(1,∞）,y(1)=α，y(∞）=β，得到了该问题的零阶渐近解。     

冷轧差厚板退火组织性能的实验研究

对CR340冷轧差厚板系列退火工艺进行实验研究,对比分析了不同退火工艺对差厚板不同厚度区组织和性能的影响,探究差厚板退火性能差异化的原因.结果表明:差厚板不同厚度区的组织性能差异取决于冷轧变形量、退火温度和保温时间.通过拟合实验数据建立了差厚板不同厚度区退火温度和保温时间与最终屈服强度和延伸率的对应关系,回归了差厚板退火后硬度与屈服强度的函数关系,为冷轧差厚板退火工艺的制定及组织性能控制提供了参考数据.     

Experiments on Sprouting Inhibition in Onions

The effect of irradiation on sprouting depends on the irradiation dose, on the irradiation time after harvest and on the physiological development stage of onions. The best conditions of an effective irradiation were found out. Experiments were carried out in order to study the physiological causes of sprout inhibition. The effect of the irradiation on cell elongation and cell division was investigated.     

Electrospinning Instabilities in the Drop Formation and Multi-Jet Ejection Part II: Various Nozzle Diameters for PVA (Polyvinyl Alcohol) Polymer Solution

Electrospinning is recognized as a simple and easy method to produce fibers with nanoscale diameters. However, the methods for controlling the shape, structure, and uniformity of electrospun fibers have not yet been fully investigated. In this research, the electrospinning jet behavior, corresponding nanofiber deposition, and average fiber diameter are examined for various nozzle diameters. Fluctuations in the sequence of drop growing, electrospinning, and/or termination of electrospinning are analyzed. We propose two different fluctuations according to nozzle diameter. The multi-jet ejections, that are closely related to the amount of nanoweb deposition and the deposition pattern, are explored.     

浅谈预应力筋的伸长与校核

钢绞线预应力混凝土在桥梁工程中已普遍使用,作为质量双控指标的钢绞线张拉伸长值及锚固张拉力的计算,相应规范均已有明确规定,但在实际施工中,对预应力张拉的具体量测却存在较大差异。文章就此问题通过深圳地铁3#线高架桥施工的实践予以介绍。     

木棉纤维拉伸性能的测试与评价

设计了单纤维强伸性能的新测试方法,测试了4种木棉纤维的拉伸性能,结果发现,木棉纤维拉伸曲线与棉纤维相似,没有明显的屈服点.木棉纤维断裂强力和断裂伸长率在一定范围内均有分布,4种木棉纤维平均断裂强力1.44～1.71 cN,平均断裂伸长率1.83%～4.23%,纤维长度、线密度与木棉纤维的断裂强力明显相关,4种木棉纤维相对断裂强度接近,而断裂伸长率差异较大,木棉纤维初始模量因其品种和产地不同存在一定差异.与棉纤维相比,木棉纤维断裂伸长率低,断裂强度和初始模量与棉纤维相近,但因木棉纤维细软而容易拉断.     

Determination of soil density by cone index data

In this paper a novel soil-density determination method is presented. The classic method (sampling, drying, mass measuring, etc.) can give proper results for the given problem but the standard methodology requires a lot of practical effort. While the soil is generally inhomogeneous, the measured density values of the soil sample applies only for the sample itself. On the entire soil territory this density can be interpreted only with significant errors. For a better mapping of the soil-density distribution expansive measurements are required. The task is complicated by the determination of density distribution in deeper layers of the soil as well. Our work presents a simpler method to determine the soil-density distribution in deeper layers with the use of cone penetration test (CI) results. With this method we can obtain detailed results of the soil-density distribution in deeper layers that may help further calculations for soil deformation analysis such as an exact determination of the soil sinkage below a tire track.