各向同性超弹性本构模型数值计算及验证

现有多种形式的橡胶本构模型试图预测橡胶力学性质,其中部分模型已写入有限元软件中用于仿真计算,还存在较多拟合性较好的模型无法在有限元材料库中直接获得。本文详述了由不变量和主伸长率描写的各向同性超弹性本构模型的数值实现方法,并结合最新的本构模型开发了UHYPER和UMAT子程序。将UHYPER用于有限元实现对多孔橡胶板的拉伸仿真,对比仿真和试验结果,验证子程序的正确性以及评估本构模型预测复杂应变场的准确性;将UMAT用于单轴、等双轴和剪切拉伸的有限元仿真,对比仿真和本构模型理论结果,验证子程序的可靠性。结果表明,有限元仿真结果与理论结果拟合较好,子程序能够契合本构模型的力学描述,所述方法可以用于超弹性材料的数值计算。     

一种土壤剖面CO2气体通量的测试方法

设计和研制了一套土壤剖面CO2气体通量原位测试的方法和装置,该方法和装置可用于土壤剖面不同深度（0～200 cm）土壤CO2气体通量的观测、不同深度土壤层CO2气体存储量的估测、土地利用/土地覆盖变化引起土壤CO2气体释放量变化的测算和估计,以及植被或地力恢复速率的评价等。     

腙类化合物的合成

芳醛和取代肼经亲核加成 消去反应合成了5个腙类化合物(3a~3e),其中香兰素腙(3a)为新化合物,其结构经¹H NMR, ¹³C NMR, IR和元素分析表征。     

Surface-relief-grating formation behavior of two hyperbranched azo polymers

In this work,surface-relief-grating formation behavior was studied by using two hyperbranched azo polymers.The hyperbranched polymers containing pseudo-stilbene type azo chromophores throughout the hyperbranched structure were synthesized by step-growth polycondensation of AB₂ type monomers.The AB₂ monomer,4-（4’-（bis（2-chloroethyl）amino）-phenylazo） benzoic acid（BAA）,was prepared through azo-coupling reaction between N,N’-bis（2-chloroethyl）aniline and 4- aminobenzenic acid.The another AB₂ monomer,4-（4’-（bis（2-chloroethyl）amino）phenylazo）-3-nitro-benzoic acid（BANA）, was prepared through azo-coupling reaction between N,N-bis（2-chloroethyl）aniline and 3-nitro-4-aminobenzcnic acid.The hyperbranched polymers（PBAA and PBANA） were prepared through nucleophilic substitution reaction of BAA and BANA, respectively.The polymers synthesized were characterized by using spectroscopic methods and thermal analysis.The photoinduced dichroism and photo-induced surface-relief-grating（SRG） formation of the hyperbranched polymers were investigated upon irradiation with Ar⁺ laser at 488 nm.PBAA shows typical photoinduced dichroism SRG formation behavior.On the contrary,PBANA does not show the photoresponsive properties.The results indicate that the nitro at the ortho position of azo group of PBANA shows the effect of inhibiting the photoinduced variations.The effect can be attributed to the blockage of the trans-cis isomerization of the azobenzene moieties by the steric hindrance.     

结合边缘信息和图像特征信息的曲波域遥感图像融合

曲波变换是一种更适合于图像处理的多尺度几何分析方法,具有比小波变换更强的方向选择和辨识能力,而且对图像边缘的表达更优于小波.结合色度-饱合度-亮度变换将其应用于合成孔径雷达图像和多光谱图像融合可以更好地表示图像中的有用特征.首先对多光谱图像进行色度-饱合度-亮度变换,得到亮度分量Ⅰ,对雷达图像和Ⅰ分量进行曲波变换得到粗尺度系数和细节尺度系数;将雷达图像的粗尺度系数和细节尺度系数进行叠加,计算归一化的曲波系数直方图,定义边缘有效因子,利用合成孔径雷达图像的特征信息将曲波变换系数分为均匀区、非均匀区和亮点目标区.然后采用相应的融合规则对融合图像的粗尺度系数进行处理,对细节尺度系数采用简单的直接取大方法,逆变换后得到新的亮度分量.用新的亮度分量替代原亮度分量进行逆色度-饱合度-亮度变换得到最终融合结果,利用统计类指标对融合结果进行评价.实验结果表明,该方法在保持光谱信息和提高空间分辨率上都有较好的效果.     

光响应性超疏水偶氮苯自组装多层膜的制备及性质研究

近年来,偶氮苯类化合物的光学顺反异构现象已引起人们的广泛关注[1~7].在紫外光照射下,偶氮苯由反式结构转变为顺式结构,引起分子的偶极矩发生变化,导致分子的吸收光谱、尺寸及表面能等均发生变化[7].偶氮苯表面能的改变可引起其表面浸润性发生变化.据文献[1~4]报道,偶氮苯膜在紫外光照射前后接触角最大改变了11°.浸润性是固体表面的一个重要特性,主要受固体表面的化学组成和微观几何结构(粗糙度)影响[8~11].通常,与水的接触角大于150°的表面称为超疏水表面;而与水的接触角小于5°的表面称为超亲水表面.本文以2-(4-偶氮苯基苯氧基)丙烯酸…     

Effect of Steam in CO2 Reforming of CH4over a Ni/CeO2–ZrO2–Al2O3 Catalyst

CO₂ reforming of CH₄ was carried out with and without steam over a Ni/CeO₂–ZrO₂–Al₂O₃ catalyst. The catalytic performance, amount of carbon deposit and the EXAFS of the Ni K-edge of samples were measured. The results show that when the catalyst is used for CO₂ reforming of CH₄ without the addition of steam, the catalyst gradually deactivates, however, addition of a small amount of steam to the feed gas can significantly inhibits the deactivation, which is due to the great suppression of coke formation on the catalyst during the reaction. The EXAFS result shows that, maybe due to the penetration of more carbon atoms into the Ni lattice, the coordination number of the nearest Ni–Ni of the sample after the reaction without steam reduces more than that of samples after the reaction with a small amount of steam in the feed gas.     

高分散锰氧化物催化剂的结构、性能及载体效应

用浸渍法制备了A l2O3,S iO2和MgO等不同性质载体负载的锰氧化物催化剂,考察了其对CO氧化反应的性能,并用XRD、XPS、TPR和XAFS等方法对催化剂进行了详细表征.活性测试结果表明,不同载体负载的样品的活性次序为:MnOx/A l2O3>MnOx/MgO>MnOx/S iO2.XRD结果表明,在S iO2和A l2O3上,负载量为15%的催化剂中没有检测到Mn氧化物的衍射峰,说明Mn物种在载体表面分散性很好,而在MgO上检测到Mg6MnO8物种.XAFS等表征结果表明,A l2O3和S iO2负载的样品中Mn主要以高分散的Mn2O3形式存在,MgO负载的样品中Mn的分散性相对较差,且与载体发生强相互作用.结合XPS和TPR结果,Mn氧化物与载体相互作用强弱的顺序为:MnOx/MgO>MnOx/A l2O3>MnOx/S iO2.负载Mn氧化物催化剂的活性与分散度没有直接对应关系,而是显示了明显的载体效应.     

The Study of Metal–Schiff Base Coordinated Polyurethane

A series of coordination polyurethanes based on novel diols bis[N-[[2-hydroxyphenyl]methylene]hydroxylethyleneamino]–copper(II), cobalt(II) and nickel (II) was synthesized successfully. The geometric structures of the metal–Schiff base, which plays an important role on the properties of these materials, were studied by extended X-ray absorption fine structure and wide angle X-ray diffraction techniques. © 1997 John Wiley & Sons, Ltd.