细纱卷绕凸轮的廓线设计修正

为了消除细纱卷绕凸轮在运转中发生的桃顶处冲击和桃底处钢领板因链条张弛而运动呆滞的故障,凸轮廓线要作修正。在桃顶处凸轮转角φ=266°～272°区间内的理论廓线试用φ的多项式取代,而在桃底处φ=0°～6°区间内的凸轮廓线则使摆杆按余弦规律运动,实验效果满意。     

气流槽聚型紧密集聚纺力矩传递分析

为了探讨气流槽聚型紧密集聚纺纱系统集聚区内的力矩传递,首先分析了集聚区内纺纱张力矩和气流力矩的传递过程,然后分析了纱线自身回转产生的扭矩与纺纱张力矩和气流力矩的关系.研究结果表明:影响力矩传递的主要参数有纺纱张力、吸气负压值等;纺纱张力矩与气流力矩决定捻度是否会越过纤维束与凹槽底部的初始接触点上传至前钳口;适当提高吸气负压值可以缓解纺纱张力.     

一种跟踪和聚光的全新理论——陈应天在太阳能利用研究领域的重大创新

陈应天教授不久前提出的跟踪聚光理论已经引起我国国家领导部门和世界范围内专家的重视.为回答对该理论的普遍存在的疑问,从光学的基本知识出发,尽量深入浅出地讨论这一理论的核心内容,如:自主创新的自旋 仰角跟踪方式,行 列驱动从镜聚光及其精度不等的不同模式,并评述该理论的优势和应用前景.     

Role of humidity on the structures and properties of regenerated silk fibers

Silk fiber was processed from highly concentrated spinning dope to solid fibers along with water removal. To understand the mechanism of water removal during silk fiber spinning process, a microfluidic chip was designed and applied to investigate the structures and mechanical properties of two kinds of regenerated silk fibroin fibers dry-spun at different relative humidity. The experimental results showed that the diameters of the fibers spun at 40% RH are always larger than the fibers spun at 50% RH due to different removal rates of water. The fibers spun at low humidity contain more β-sheet structure and lower degree of chain orientation and crystalline orientation. These results indicate that the fast phase transition of silk fibroin from sol–gel to silk fiber undergoes with rapid water removal and higher fiber orientation relates to more residue water and drawing force.     

基于EMD算法的空间自旋目标平动补偿与微动特征提取

针对微多普勒频率附加在空间目标高速轨道运动产生的多普勒频移上使微动特征提取更加困难这一问题,提出了一种利用EMD算法对空间目标进行精确平动补偿和微多普勒特征提取的方法。对空间自旋目标进行建模,推导了窄带雷达条件下空间目标的微多普勒效应,并分析了平动分量对微多普勒的影响;把目标回波分解成一系列本征模态函数(IMF),然后求出瞬时频率,利用经验模型分解(EMD)算法对瞬时频率进行分解,分析各分量的能量百分比判别平动频移分量,实现回波信号的平动补偿;对平动补偿后的信号利用 EMD算法分离出微多普勒曲线,提取微动特征。仿真实验验证了该方法的可行性与有效性。     

Study on the Model of Thermal Channel Spinning Process for PET Polymer

A mathematical model to describe the TCS process inPET high-speed melt-spinning is established.The de-velopment of crystallinity,molecular orientation andmorphological features of high-speed-spun PET fiberin TCS process is investigated at take-up speeds rangingfrom 3600-4400 m/min and thermal channel tempera-tures ranging from 160-200℃ by simulation.The pro-files of tensile force,running velocity,temperature,bi-refringence,crystallinity and diameter in the TCS spin-line for various process conditions are obtained.Thepredicted results using this model are compared with themeasured crystallinty,diameter and birefringence.Theresults indicate that they are in fairly good agreement.The"necking point"in the TCS spinline can be predictedby this model,and its position changes with the corre-sponding process parameters such as take-up speed andthermal channel temperature.It is found that the neck-ing point moves towards the spinneret when the take-upspeed or the thermal channel temperature increases.     

化纤丝束吹风冷却装置研究进展

综述了化纤熔融纺丝冷却吹风装置及丝束冷却过程中冷却风流场仿真的研究进展.讨论了针对吹风装置冷却风不均匀、不稳定、提高丝束质量、降低装置能耗等问题所采取的相关对策与措施.对吹风冷却装置的研究和应用前景进行了展望.     

环锭纺纱线气圈的研究

用圆柱坐标系建立纱线微段的微分方程,用数值方法求解可获得气圈形态及其纱线受力的精确解。用解析方法建立气圈形态及其纱线受力的近似解析表达式,可反映气圈各参数对形态或受力的影响,其分析过程清晰、简捷的特点显著。两种计算结果的相对误差甚微。     

转杯纺杯内纱段捻度分布研究

通过对纱条在假捻盘上的运动和受力分析,对转杯纺杯内的捻度分布进行研究,并得到了杯内捻度分布的一般规律.     

高浓度PAN/DMSO原液粘度特性及纺丝工艺性的研究

在研究了聚丙烯腈／二甲基亚砜纺丝溶液粘度特性的基础上,初步探讨了纺丝液中ＰＡＮ的质量分数与纤维的可牵伸性及致密性的关系。