氟代甲酰胺和N—氟代甲酰胺异构化反应路径的理论研究

采用量子化学MNDO法,计算了氟代甲酰胺和N—氟代甲酰胺的1,2—氢迁移异构化反应势能面上的反应路径。结果表明:氟代甲酰胺分子比N—氟代甲酰胺分子稳定.前者异构化为吸热反应,后者为放热反应。N—氟代甲酰胺的氢迁移势垒低于甲酰胺的氢迁移势垒.氟原子的存在使过渡态结构相对松散,有利于异构化的发生.     

结晶碳酸钕的水热合成、外观形貌及其组成

Crystalline neodymium carbonates were prepared by treating the amorphous precipitate formed from the reaction between neodymium chloride and ammonium bicarbonate under hydrothermal condition. Their composition, morphology and crystal phase were identified by means of elemental analysis, SEM and XRD. It was found that Nd₂(CO₃)₃·2.5H₂O with tengerite-type structure and sheet morphology was obtained when the feed molar ratio(FMR=n_(NH4)2CO2/n_NdCl3)was 2 or 1.8 and hydrothermally treated at 150 ℃ for 12h. However, orthogonal NdOHCO₃ particles agglomerated with long rod crystals were formed when lowering FMR to 1.5 under the same hydrothermal condition. Phase transformation from tengerite-type Nd₂(CO₃)₃·2.5H₂O to orthogonal NdOHCO₃ was occurred when increasing hydrothermal temperature or prolonging hydrothermal time, which is beneficial to the preparation of neodymium hydroxyl-carbonate with neodymium oxide content higher than 70%.     

玻璃澄清剂中砷和锑的联合测定

常用的玻璃澄清剂有硝酸盐、硫酸盐、铵盐、氟化物、稀土矿物、三氧化二砷、三氧化二锑等。利用稀土元素作玻璃澄清剂，澄清效果好，污染小，但其价格较高，我国一些大型玻璃制造企业采用氧化铈作为澄清剂，而更多的小企业采用白砒、砷锑矿物及废渣等为澄清剂。使用含砷、锑的玻璃澄清剂，尤其是含砷的玻璃澄清剂，     

2—（芳磺酰基）—1—（2—噻吩基）乙酮的合成

２－（芳磺酰基）－１－（２－噻吩基）乙酮的合成丁言斌樊爱龙张正＊（南京大学化学系南京２１００９３）关键词氯噻吩基乙酮，芳磺酰基噻吩基乙酮，合成，相转移催化１９９６－０８－１２收稿，１９９７－０１－１３修回砜类化合物不仅是有机合成的有用中间体［１］，而...     

238U(n,f)短寿命产物核累积产额的评价(英文)

为满足堆内或核爆中链式反应过程的燃耗值的计算需要，对裂变谱中子和14MeV中子诱发238U裂变的短寿命产物核的累积产额进行了评价。评价利用了所有可利用的实验数据， 经物理分析后， 使用AVERAGE程序加权平均， 用ZOTT程序进行同时评价， 给出了所要求能点的唯一最佳推荐数据， 并将评价结果与ENDF/B-VII， JEF-2.2， JENDL-3.2和CENDL-2的推荐数据进行了比较。 评价结果将用于CENDL-2的更新与升级。For reliable and consistent nuclear calculation, the cumulative yields for short lived fission products are evaluated based on the available experimental data for 238U fission induced by fission spectrum neutrons and ~14 MeV neutrons. The data are processed using codes AVERAGE for weighed average and ZOOT for simultaneous evaluation. The evaluated data are compared with those in the major international nuclear data libraries, including ENDF/B-VII, JEF-2.2, JENDL-3.2 and CENDL-2. The present evaluation will be used to improve and update the CENDL-2 library.     

基于凸集模型结构稳健性优化设计

不确定性因素大量存在于实际工程中,采用凸集变量描述结构不确定性参数,进一步将凸集模型划分为超椭球模型和区间模型。由试验点数量确定选用两类模型的标准,从本质上指明了两类模型的区别。分别对两类模型中不确定变量进行标准化,通过对比分析,阐述了基于超椭球模型和区间模型优化方法和求解过程的共同点与区别。借用超椭球模型分析思路,对优化过程中的变量进行分类,为突出稳健性优化设计特点,考虑约束条件从特殊到一般,重点描述基于区间模型稳健性优化的基本思想方法。采用目标性能分析方法,强调指定可靠性指标的唯一性,给出了稳健性优化的具体算法、求解步骤和迭代收敛准则。对实际算例进行了分析与求解,与已有结果比较,验证了本文方法的正确性和有效性。     

基于信息理论的航天相机性能评价研究

基于Shannon公式,提出了一种综合评价航天相机性能的新判据。给出了用系统的调制传递函数(MTF)与信噪比(SNR)的乘积大于或等于9来综合评价航天相机性能的方法。该方法为航天高分辨率相机的研制提供了参考。由于这个结论没有针对具体的相机,因而具有普遍的意义。     

Material microstructures analyzed by using gray level Co-occurrence matrices

The mechanical properties of materials greatly depend on the microstructure morphology. The quantitative characterization of material microstructures is essential for the performance prediction and hence the material design. At present,the quantitative characterization methods mainly rely on the microstructure characterization of shape, size, distribution,and volume fraction, which related to the mechanical properties. These traditional methods have been applied for several decades and the subjectivity of human factors induces unavoidable errors. In this paper, we try to bypass the traditional operations and identify the relationship between the microstructures and the material properties by the texture of image itself directly. The statistical approach is based on gray level Co-occurrence matrix(GLCM), allowing an objective and repeatable study on material microstructures. We first present how to identify GLCM with the optimal parameters, and then apply the method on three systems with different microstructures. The results show that GLCM can reveal the interface information and microstructures complexity with less human impact. Naturally, there is a good correlation between GLCM and the mechanical properties.     

磁控溅射Cu薄膜的光电性能研究

利用磁控溅射技术,通过正交试验设计方法,在K9光学玻璃基底上制备了Cu薄膜,研究了溅射时间、基底温度和氩气流量对Cu薄膜光电性能的影响.研究表明:Cu薄膜的透射谱在紫外波段362 nm处有明显吸收峰,但在可见光波段吸收强度较弱,说明Cu膜在可见波段有较高的透光性;膜厚度增加则光学透射率降低.电阻率随膜厚的增大,大体上呈逐渐减小的趋势;1100 nm 为临界尺寸,Cu膜厚度<1100 nm时,电阻率值变化较快;Cu薄膜厚度>1100 nm时,电阻率变化缓慢至定值.当溅射时间为25 min、基底温度为300 ℃、氩气流量为6.9 sccm时所得样品在紫外-可见光区没有吸收,且导电性好.     

放电等离子烧结镓掺杂氧化锌陶瓷及其电学特性研究

采用放电等离子烧结(SPS)方法烧结出了致密的掺镓氧化锌陶瓷(0.075wt; GZO).样品的烧结温度为950～1200℃,烧结时间为3～21 min,并对样品的物相、断口形貌、电学性能以及密度进行了测试和分析.结果表明,烧结条件对GZO的晶体结构没有影响,但是对样品的密度、晶粒尺寸、电阻率等性质有一定的影响.综合分析上述结果可得到用SPS方法烧结GZO陶瓷的最佳烧结工艺是烧结温度1100℃,烧结时间9 min.