空压机气量调节机构的改进设计

由于实际应用环境的差异、年久老化以及制造精度未能达标等原因，一些企业的生产设备常常出现故障．针对5L-40／8型空压机气量调节机构的问题——吸气阀顶开架动作不灵活这一实际情况，提出了相应的改进措施，并付诸实施，实际应用表明这种方法是可行的，取得了令人满意的效果．     

结合小波预处理的图像编码方案

提出了一种新型的结合小波预处理的图像编码方案，在编码端，首先对原始图像进行模糊化处理，然后再按照通常的小波变换进行编码；在解码端，先进行小波变换，然后再进行与模糊化相反的清晰化处理，得到恢复图像，试验结果表明该编码方案在计算复杂度上上升极少，在恢复图像质量上下降很少，但是在图像压缩比上得到大幅度的提高，是提高小波变换图像编码效率的理想方法。     

空间刀具半径补偿后置处理的研究

文章提出了一种空间刀具半径补偿后置处理方法，自主开发了五轴机床的后置处理软件。经过验证，基本满足工程使用的要求。这种算法依托现有的CAM软件和CLF格式的刀轨文件，具有一定的通用性，既可以生成带有补偿信息的数控代码，又对开发带有半径补偿功能的五轴数控系统有一定的参考价值。     

Microstructure and fracture toughness of electron beam welded joints of 30CrMnSiNi2A steel

Two post-weld heat-treatments ( PWHT) , 900℃ oil quenched and low temperature tempered (PWHTA) and high temperature tempered and then 900~C oil quenched and low temperature tempered ( PWHTB ) , are employed to treat the weldment. Then the effect of two post-weld heat-treatment processes on the microstructure, mechanical properties and fiacture toughness of electron beam welded joints of 30CrMnSiNt‘2A steel have been discussed. The results show that, after two kinds of PWHT the microstructure and hardness at every zones of EBW joints are nearly same. Although the welds have good mechanical properties, fiacture toughness of both weld and heat-affected zone (HAZ) is low, the CTOD values of welds are comparatively higher than that of HAZ. Microstructure and fiacture toughness of two EBW joints have no evident differences.     

康凯对乙草胺造成大豆药害的缓解效果

乙草胺是一种酰胺类除草剂,在我国北方大豆田用量较大,但由于使用技术及气候因素等常出现药害问题。评价了康凯对乙草胺药害的缓解效果,结果表明康凯用量0．102ga．i．／hm^2施后10-20d,可明显改善大豆体内的GSH含量、GST和SOD活性,提高大豆的株高和叶面积。     

Synthesis and characterisation of a modified crosslinkable polyurethane non-linear optical polymer

The hydroxyl groups formed during the reaction of DGEBA (diglycidyl ether of bisphenol A) and aniline are used for the first time to form crosslinkable polyurethane. The very active diisocyanate groups as a pure reagent are only introduced to the reaction system at the last step of the crosslinking reaction, which greatly improves the preparation procedure. A very good film-forming property was found and a d₃₃ value as high as 320 pm V⁻ was measured for the poled polymer film. Copyright © 2000 John Wiley & Sons, Ltd.     

Kinetics of copolyurethane network formation

Cure kinetics for the formation of copolyurethane networks of various compositions based on hydroxy-terminated polybutadiene (HTPB), poly(12-hydroxy stearic acid-co-TMP) ester polyol(PEP), and different isocyanates has been studied through viscosity build up during the cure reaction. The viscosity(N)—time (t) plots conform to the equation N = ae^bt, where a and b are empirical constants, dependent on the composition and the nature of the polyols and the isocyanates. The rate constants (k) for viscosity build up, evaluated from the slopes of dN/dt versus N plots at different temperatures, were found to vary significantly from 0.0073 to 0.25 min⁻¹; and the activation energies for gelation were found to be in the range 20 to 40 kJ mol⁻¹. The results have been interpreted in terms of the dependence of the rate constants on structural characteristics of the prepolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1795–1801, 1997     

Non‐linear analysis of thin‐walled members of open cross‐section

The paper presents a means of determining the non‐linear stiffness matrices from expressions for the first and second variation of the Total Potential of a thin‐walled open section finite element that lead to non‐linear stiffness equations. These non‐linear equations can be solved for moderate to large displacements. The variations of the Total Potential have been developed elsewhere by the authors, and their contribution to the various non‐linear matrices is stated herein. It is shown that the method of solution of the non‐linear stiffness matrices is problem dependent. The finite element procedure is used to study non‐linear torsion that illustrates torsional hardening, and the Newton–Raphson method is deployed for this study. However, it is shown that this solution strategy is unsuitable for the second example, namely that of the post‐buckling response of a cantilever, and a direct iteration method is described. The good agreement for both of these problems with the work of independent researchers validates the non‐linear finite element method of analysis. Copyright © 1999 John Wiley & Sons, Ltd.     

Laser interferometric technique for measuring polymer cure kinetics

An optical interference apparatus for the analysis of polymer curing kinetics is described. The device employs a helium‐neon laser and a home‐built Michelson interferometer to measure refractive index variations and film thickness variations during film polymerization. The refractive index variation provides a phenomenological measure of the extent of cure. The technique is demonstrated by collecting interferometric curing profiles for a UV photocurable acrylate resin formulation. Systematic comparisons of curing profiles are made as a function of UV illumination intensity and photoinitiator concentration. Several aspects of the curing process are characterized by these interferometric measurements, such as film shrinkage, gel point formation, and the kinetics of photopolymerization inhibition. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2133–2142, 1999     

Cure properties of epoxies with varying chain length as studied by DSC

The cure of diglycidyl ether of bisphenol A (DGEBA) and a homologous series of poly(ethylene oxide) diglycidyl ether (PEODE) epoxy resins with 4,4′‐diaminodiphenyl sulfone (DDS) was studied by scanning and isothermal differential scanning calorimetry (DSC). The heat of polymerization was relatively independent of monomer structure and chain length when determined by isothermal DSC. Variations in the heats of polymerization determined by the scanning method were attributed to degradative reactions at higher temperatures during the scan. The activation energies determined by scanning DSC experiments were relatively constant at 61 ± 3 kJ/mol. However, using an isothermal cure method, the activation energies were found to vary with monomer structure and extent of cure. The isothermal kinetics were analyzed in terms of the autocatalytic model on the basis of competing reaction paths involving catalysis by either initial impurities or hydroxyl groups produced in situ. The activation energies of both reaction paths were found to vary with monomer structure and degree of conversion. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1479–1488, 1999