增材制造设计(DfAM)下的金刚石晶格结构研究

基于机械零件的增材制造设计,用仿自然式方法设计了一种金刚石晶格结构,对晶胞相对密度和等效弹性模量建立了数学模型,并拟合得到二者关系式,一系列的仿真验证结果显示理论研究所得关系式具有一定的正确性;对金刚石晶格填充结构提出变密度假设,并用仿真和压缩试验的方法进行了验证,结果显示,填充单元密度以受力点为中心渐渐减小的变密度结构拥有更好的抗压性能,同时验证了本文得出的等效弹性模量数学模型具有一定的正确性和适用性.本研究结果可应用于承压机械零件的实体夹层填充,对机械零件进行应力匹配变密度设计,以达到机械结构轻量化的目标.     

车门铰链系统与车门下沉刚度的相关性

针对某型车门下沉问题,通过台架试验获得车门、铰链和车身等各单因素下沉量和车门绞链系统整体下沉量,对单因素下沉量与系统整体下沉刚度进行线性拟合分析,得到车门铰链系统各单因素与系统下沉刚度的相关度排序.对前、后车门分别选取相关度较高的单因素进行优化,最终改进方案的仿真和试验结果证明该方案可有效地提升车门下沉刚度.采用定量分析法可快速找出影响下沉刚度的敏感因素,并能够快速生成优化方案,为新车型设计提供参考.     

Corrosion behaviour of Mg-Gd-Y-Zn-Ag alloy components with different sizes after cooling

The corrosion behaviour of Mg-6Gd-3Y-1Zn-0.3Ag (wt.%) alloy components with different sizes after cooling was investigated. The alloys in the small components (SC) cooled fast, which were composed of α-Mg matrix and coarse long-period stacking ordered (LPSO) phases. The alloys in the large components (LC) cooled slowly, and there were thin lamellar LPSO phases precipitating inside the grains, except for α-Mg matrix and coarse LPSO phases. The hydrogen evolution test revealed that the corrosion rate of LC sample was higher than that of SC sample. Electrochemical impedance spectroscopy (EIS) test showed that the surface film on LC alloys provided worse protection. The corrosion morphologies indicated that the precipitation of the thin lamellar LPSO phases in LC sample caused severe micro-galvanic corrosion, which accelerated the rupture of the surface film.     

Multi-color Q-switched of neodymium-doped all-fiber laser based on tungsten disulfide saturable absorber

Journal of Materials Science: Materials in Electronics - In this paper, a Q-switched and three-color operation of Neodymium-doped silica all-fiber laser is realized, in which, a few-layer...     

大鲵肝茶叶水提液脱腥过程中挥发性有机物的动态变化

目的：探讨茶叶水提液对大鲵肝的脱腥效果。方法：采用感官腥味值结合气相—离子迁移色谱(GC-IMS)分析经茶叶水提液处理不同时间(0，5，10，15，20 min)大鲵肝中挥发性成分的变化。结果：与未脱腥组相比，经茶叶水提液脱腥处理5 min后大鲵肝脏腥味值显著下降(P＜0.05)，处理10 min后腥味值基本稳定。不同脱腥时间下大鲵肝样品中共鉴定出32种挥发性有机物，包括10种醇类、8种醛类、5种酯类、5种酮类、3种烯烃类和1种醚类。经脱腥处理后，大鲵肝中醇、烯烃、醚、酯类物质相对含量下降，酮类和醛类物质相对含量增加。通过正交偏最小二乘法判别分析(OPLS-DA)结合变量投影重要性(VIP)筛选出10种潜在特征标志物(VIP＞1)，包括4种酮类、2种醇类、2种醛类、1种烯类和1种醚类。随着脱腥时间的延长，蘑菇醇、2-丁酮二聚体、异戊醇单体、2-丁酮单体相对含量呈降低趋势，而正己醛单体、异戊醛单体、丙酮相对含量呈增加趋势。结论：茶叶水提液处理5~10 min能够明显降低大鲵肝腥味，通过GC-IMS技术结合多元统计分析可以对脱腥过程中大鲵肝挥发性有机物进行区分。     

ZnO·2.7Al2O3 nanocomposite with high optical transparency

Here we report a transparent dual-phase ZnO·2.7Al₂O₃ ceramic. The composite is pore-free and consists of thin nanosheets with a spinel phase and a hexagonal phase, while the two phases match closely in both lattice and refractive index. Such features result in excellent optical transmittance (maximum value >80% in the visible spectrum) at comparable phase volume. This work may provide a new thought for the rational structural design of optical nanocomposites.     

冰下单载波水声通信试验研究

北极地区战略地位的提高促进了极区各种应用的快速发展，冰下水声通信成为其中一个热点问题。为了研究冰下单载波水声通信性能，在黄海冰区开展冰下试验。重点分析了内嵌锁相环的多通道判决反馈均衡(Multi-channelDecision Feedback Equalization, M-DFE)技术在冰下水声通信中抗多途时延的能力，研究比较了改进比例归一化最小均方(Improved Proportional normalized Least Mean Square, IPNLMS)算法和递归最小二乘(Recursive Least Squares,RLS)算法的均衡性能。试验结果表明IPNLMS和RLS都能克服信道多途效应带来的影响。在牺牲计算复杂度的前提下，RLS具有更好的均衡效果，M-DFE在冰下环境中能够有效消除码间干扰。