氧化锌-辛酸亚锡催化合成丙交酯

采用氧化锌和辛酸亚锡为催化剂,在高真空条件下共同催化合成丙交酯.比较了两种催化剂加入方式的不同对丙交酯产率的影响,发现当脱完自由水后同时加入氧化锌(ω=1%)和2 mL辛酸亚锡,丙交酯的粗产率可以达到90%以上.     

蜻蜓翅膀微观结构及其润湿性

利用视频光学接触角测量仪对6种蜻蜓翅膀表面的接触角进行了测量,发现蜻蜓翅膀具有疏水性能,接触角在135.14°~149.85°之间,其值与测量部位无关,与蜻蜓种类有关。用扫描电子显微镜对蜻蜓翅膀表面微观结构进行观测,发现蜻蜓翅膀上布满柱状纳米级结构形态,柱直径分布范围为66.90~200.73 nm,柱间距为20.00~650.00 nm,翅膜厚度为1.58~4.08μm。分析了蜻蜓翅膀表面疏水机理,研究表明:蜻蜓翅膀的疏水机理满足Cassie模型,其疏水性能主要由体表纳米级别的柱状结构与体表成分共同作用的结果。蜻蜓翅膀润湿性能的研究为微型飞行器及自清洁材料的制备提供了理论依据。     

A comparison of the predictive capabilities of current failure theories for composite laminates,judged against experimental evidence

This paper draws together the results from a co-ordinated study, known as the World-Wide Failure Exercise, whereby 12 of the leading theories for predicting failure in composite laminates have been tested against experimental evidence. The comparison has been effected through 14 carefully selected test cases, which include biaxial strength envelopes for a range of unidirectional and multi-directional laminates, and stress–strain curves for a range of multi-directional laminates, loaded under uniaxial or biaxial conditions. The predictions were provided by the originators of the theories, not by third parties, and were made without access to the experimental results beforehand. The predictions and experimental data have been compared in a systematic and detailed manner, to identify the strengths and weaknesses of each theory, together with a ranking of the overall effectiveness of each theory. Careful reading of this analysis and study of the figures provided will inform the reader when selecting an appropriate failure theory for use in a given design situation. It will also provide a qualitative assessment of the likely accuracy and reliability of the prediction in a given circumstance.     

Strength prediction of bolted joints in graphite/epoxy composite laminates

A parametric finite element analysis was conducted to investigate the effect of failure criteria and material property degradation rules on the tensile behaviour and strength of bolted joints in graphite/epoxy composite laminates. The analysis was based on a three-dimensional progressive damage model (PDM) developed earlier by the authors. The PDM comprises the components of stress analysis, failure analysis and material property degradation. The predicted load–displacement curves and failure loads of a single-lap single-bolt joint were compared with experimental data for different joint geometries and laminate stacking sequences. The stiffness of the joint was predicted with satisfactory accuracy for all configurations. The predicted failure load was significantly influenced by the combination of failure criteria and degradation rules used. A combination of failure criteria and material property degradation rules that leads to accurate strength prediction is proposed. For all the analyses performed, the macroscopic failure mechanism of the joint and the damage progression were also predicted.     

高精度地磁数据采集板的设计

为了满足高精度地磁数据采集的需要,本文提出一种在磁通门磁传感器基础上,使用ADS1282搭配C8051F340单片机搭建四通道32位高精度地磁场数据采集板的设计方法。与现有地磁采集器相比,该方法设计的采集板具有低噪声、大动态范围、低功耗和多通道等优势。经实验室和野外测试,系统工作稳定,采集到的数据质量高,并解决了现有设备不能在野外长期数据采集的不足。     

Seismic performance evaluation procedure of asymmetric plan structures

Plan asymmetry leads to lateral-rotational coupled effects on structural response characteristics.This investigation deals with a simplified method for performance estimation of structures with asymmetric plan.By taking the eccentric characteristics of structures into account,an equivalent triple-degree of freedom (ETDOF) system,which is constructed by eccentric mass,rigid links and springs,is proposed.The modal pushover analysis (MPA) method for asymmetric plan structures is proposed.The target displacement is determined by constant strength spectrum.The applicability of proposed method is discussed.A generic mass eccentric 4-story steel frame is analyzed by the proposed MPA procedure and nonlinear time history analysis (NTHA).The results show that the maximum deformation obtained from MPA has a good agreement with the NTHA results.The proposed MPA procedure is reliable and effective for evaluating the performance of asymmetric plan structures.     

大孔树脂法分离纯化荚果蕨总三萜

目的:筛选出分离纯化荚果蕨总三萜的最佳大孔树脂型号及工艺条件。方法:以荚果蕨总三萜浓度为指标,通过静态和动态实验,筛选最佳大孔吸附树脂并初步确定总三萜纯化工艺。结果:AB-8型大孔树脂吸附解析效果最好,吸附条件:溶液浓度1.96mg/m L,p H为6,流速1.5m L/min,吸附体积5BV;洗脱条件:60%乙醇,流速2.0m L/min,洗脱体积4BV,其回收率为86.27%,纯度82.32%,精制倍数为2.88。结论:AB-8大孔树脂较适合分离纯化荚果蕨总三萜。该工艺简单可行,纯化效果好,可为工业生产中分离纯化荚果蕨总三萜提供理论指导和参考依据。