同轴电缆皱纹铜管外导体激光焊接工艺

提出了一种采用激光焊接皱纹铜管外导体的同轴电缆的制造工艺.该制造工艺改变原有使用氩弧焊的常规铜管焊接工艺,使微小型皱纹铜管外导体的焊接从理论探索演变为实际操作.激光焊接法生产的微小型皱纹铜管外导体同轴电缆,在电性能和机械性能方面都取得了令人满意的效果.     

影响射频同轴电缆衰减的因素

本文对影响射频同轴电缆衰减的几个因素进行了分析,在分析中考虑到了电缆中空气层的存在,引入了等效绝缘层的概念。     

带栓钉波形钢板混凝土组合构件粘结滑移性能与承载力试验研究

通过11个带栓钉的波形钢板混凝土组合构件在单调荷载下的推出试验和1个自然粘结构件的对比试验,研究带栓钉波形钢板混凝土组合构件的破坏形态、裂缝模式、荷载-滑移特性、波形钢板应变分布和承载力等。结果表明:带栓钉波形钢板混凝土组合试件的破坏形态以混凝土劈裂为主。试件的荷载-滑移曲线由上升阶段、下降阶段、残余阶段三个部分组成。由于混凝土和栓钉的组合作用,波形钢板自由端存在受拉区,产生过零点现象。带栓钉波形钢板混凝土组合试件的抗剪承载力随栓钉直径、数量的增长呈线性增长,而在一定条件下,栓钉长度、钢板厚度对抗剪承载力影响不大,另外在200 mm范围内适当增大栓钉间距对抗剪承载力也有提高。基于试验结果和力的扩散原则,分别提出了考虑栓钉影响的波形钢板混凝土界面粘结滑移本构模型以及带栓钉的波形钢板混凝土推出试件的承载力计算公式,所提模型与试验结果吻合良好,承载力公式计算结果与试验结果总体相符且偏于安全。     

波纹管补偿器在管网中静压轴向推力的计算

波纹管补偿器在大口径管网中,盲板力在管网固定支架的受力计算中是一个很重要的参数.通过采用物体受力平衡切面法和积分法,分别对U型平波纹管和Ω型波纹管补偿器的盲板力的计算进行定量分析计算,论证了波纹管补偿器盲板力的计算方法应当是波补的最大直径或最大直径轴向投影面积与介质压强的乘积,而不是波补的平均直径或最大直径轴向投影面积与介质压强的乘积,从而使盲板力的计算结果更加准确.     

牛至精油涂膜瓦楞纸箱对草莓保鲜效果的研究

将牛至精油与β-环糊精、壳聚糖复配制成复合涂膜液,涂布于瓦楞纸箱内表面制得具有抗菌功能的瓦楞纸箱,研究常温条件下(16～18℃,33%～35%RH)该瓦楞纸箱对草莓的保鲜效果。结果表明:当瓦楞纸箱中牛至精油、β-环糊精与壳聚糖的涂布量分别为1.52、6.4、8 g/m2时,可以较好地维持草莓的外观品质,与空白对照组相比,可以降低草莓腐烂率68.75%,延长草莓贮藏期3 d。     

Experimental investigation of forced flow boiling of nitrogen in a horizontal corrugated stainless steel tube

Experimental investigation is performed on the heat transfer characteristics of forced flow boiling of saturated liquid nitrogen (LN₂) in a horizontal corrugated stainless steel tube with a 17.6 mm maximum inner diameter. The local heat transfer coefficients (HTCs) are measured at two mass flow rates with a wide range of wall heat fluxes. The effects of the heat flux, mass flow flux and vapor quality on the two-phase heat transfer characteristics are discussed. The results reveal that the local HTCs increase with the heat flux and mass flow flux. The measured local HTCs present a strong dependence on the heat flux. The circumferential averages of the HTCs for the present corrugated tube are compared with the empirical correlations proposed for the smooth tubes, and the results show that the heat transfer is enhanced due to the area augmentation.     

一种新型包装专用蜡的研制

为了根据某瓦楞纸箱生产厂的实际生产条件制备一种耐热、耐低温、防水、透气等性能优异的包装专用蜡，将58号全炼蜡和70号微晶蜡混合物作为基础蜡料，分别考察添加剂、助剂、抗氧剂等对基础蜡料滴熔点、运动黏度及外观等的影响，确定了最佳制备配方：合成蜡、添加剂B、助剂1、助剂2、抗氧剂加入量（w）分别为基础蜡料质量的9.8%，6.5%，1.5%，2.1%，0.1%。在温度为160 ℃、时间为30 min、搅拌速率为200 r/min条件下制备的包装专用蜡具有熔点高、黏附性强、光泽性好的优点，满足该瓦楞纸箱生产厂的质量和外观要求。     

三种形状柔性铰链转动刚度的计算与分析

本文针对3种形状的柔性铰链进行力学分析，推导出它们各自绕z轴的转动刚度计算公式；通过计算、比较和分析得出柔性铰链中外形、几何尺寸等设计参数对转动刚度的影响程度。根据分析结果确定3种形状柔性铰链各自的微制造工艺及适用场合，为MEMS中柔性铰链的设计与应用提供一定的依据。     

Deformation and compressive strength of corrugated cartons under different indentation shapes: Experimental and simulation study

A new method to enhance the compressive strength of corrugated cartons is proposed in this study. The work aims to carry out compression tests on the corrugated carton to analyze the deformation and compressive capacity of the carton under the indentation condition of different shapes. First, compression tests are carried out on nonindentation cartons, one-line indentation cartons, unclosed rhombus indentation cartons, rhombus indentation cartons, and cross-indentation cartons to record their maximum compressive force. Second, by comparing the deformation of different cartons, it is found that rhombus indentation and cross-indentation have the greatest influence on the compressive strength of cartons. Rhombus indentation will enhance the compressive strength of the carton, while cross-indentation will reduce it. Third, ANSYS Workbench is used to analyze the buckling of cartons, and the maximum compressive force of nonindentation cartons and rhombus indentation cartons is obtained. Finally, through the comparison of the finite element method and experiments, it is concluded that rhombus indentation can improve the compressive strength of cartons, which is of great significance to the industrial production of cartons.