氨合成-水热改性法制备氢氧化镁阻燃剂

为了解决氢氧化镁和聚合物之间的不相容问题, 对氨合成法-水热改性处理2步法制备高分散氢氧化镁阻燃剂进行了研究,分析了常温合成温度、水热改性温度和水热改性时间对制备大晶型、低比表面积氢氧化镁阻燃剂的影响.结果表明,经过水热改性处理改变了氢氧化镁晶体的生长习性,生成了形貌规则、粒径分布均匀、分散性良好的氢氧化镁六方片状颗粒.另外通过提高氯化镁浓度和氨水过量1倍,探讨了常温合成反应的转化率,认为应该在反应原料等当量下寻求提高转化率的可行方法.     

On initial steps of chemical prebiotic evolution: Triggering autocatalytic reaction of oligomerization

Searching for extraterrestrial life attracts more and more attention. However this searching hardly can be effective without sufficiently universal concept of life origin, which incidentally tackles a problem of origin of life on the Earth. A concept of initial stages of life origin is stated in the paper. The concept eliminates key difficulties in the problem of life origin, and allows experimental verification of it. According to the concept the predecessor of living beings has to be sufficiently simple to provide non-zero probability of self-assembling during short (in geological or cosmic scale) time. In addition the predecessor has to be capable of autocatalysis, and further complication (evolution). A possible scenario of initial stage of life origin, which can be realized both on other planets, and inside experimental facility is considered. In the scope of the scenario a theoretical model of multivariate oligomeric autocatalyst is presented. Results of computer simulation of two versions of oligomeric autocatalytic reactions are presented. It is shown that the contribution of monomer activation reaction is essential, and in some cases autocatalysis in polymerizing reaction can be achieved without catalyzing proper monomer binding reaction.     

双级高压涡轮气动性能试验状态模化方法

针对双级高压气冷涡轮的低温试验状态模化方法，对以空气为工质、基于不同相似准则数的试验模化状态的流场相似 性进行数值仿真。结果表明：对于有冷气试验模化方法，采用出口马赫数与设计状态一致的模化方法可获得相似性较好的试验状 态流场，此时反力度、载荷系数、马赫数均能保证良好的相似性，主要相似准则数偏差不超过5%；对于无冷气试验模化方法，保持 涡轮几何不变并增大膨胀比使得等熵速比与设计状态的一致，或通过改变叶片数保证各排出口马赫数与设计状态的一致，均能显 著改善无冷气模化状态与设计状态的流场相似性。其中前者反力度相似性接近98%，而后者载荷系数和马赫数的相似性达到了 同样水平，但破坏了模型的几何相似。     

单循环脉冲爆轰发动机内外流场的动力学结构

对脉冲爆轰发动机由高温火团引发的甲烷-空气混合气体爆轰过程和管内、外轴对称流场分布进行数值模拟,考虑了CH4-O2-N2的19个基元反应和14种组份。计算结果反映了爆轰管出口端附近区域的激波衍射,涡环及复杂的涡与激波相互作用情况等,描绘了管内、外流场的动力学结构。     

ZnMnO3及LaZnMnO3的制备及结构特性

对ZnO与MnO2固相反应进行研究,当烧结温度超过1300℃和烧结时间超过12h,ZnO与MnO2固相反应生成ZnMnO3的四面体结构.对La1-xZnxMnO3材料的制备条件进行研究,对结构进行表征.研究结果表明,固相反应只与烧结温度和烧结时间有关,与压制压力没有太大关系.当烧结温度超过1300℃和烧结时间超过6h,X射线衍射谱表明都具有钙钛矿衍射峰,但掺杂浓度在50%～70%时有新的衍射峰,可能产生了新相,有待进一步深入研究.     

离解反应速率常数中的方位因素

以碰撞理论为基础探讨了结构方位因素对离解反应速率常数的影响,建立了计及方位特征的离解反应模型,计算对比了热平衡假设下空气中几个典型的离解反应的Arrhenius图.结果表明,在所选实例中,除了反应N₂+N和O₂+O外,考虑方位因素后确实能够更好地理论估算出反应速率常数.对上述例外文中做了一定的讨论.     

电子束固化环氧树脂的引发和增长反应速率

对二苯基碘 鎓 六氟磷酸盐引发的环氧树脂电子束(EB)辐射固化反应动力学进行了研究,应用环氧树脂乙腈溶液推导出引发剂辐射分解速率常数和引发、增长反应速率.动力学研究结果表明,二苯基碘 鎓六氟磷酸盐引发剂经电子束辐射分解产生质子酸的过程是二级反应,在辐射反应过程中,环氧树脂体系的引发速率和增长速率分别迅速达到最大值后逐渐减小.      

An integrated graphic–taxonomic–associative approach to analyze human factors in aviation accidents

Human factors are critical causes of modern aviation accidents. However, existing accident analysis methods encounter limitations in addressing aviation human factors, especially in complex accident scenarios. The existing graphic approaches are effective for describing accident mechanisms within various categories of human factors, but cannot simultaneously describe inadequate human–aircraft–environment interactions and organizational deficiencies effectively, and highly depend on analysts' skills and experiences. Moreover, the existing methods do not emphasize latent unsafe factors outside accidents. This paper focuses on the above three limitations and proposes an integrated graphic–taxonomic–associative approach. A new graphic model named accident tree(AcciTree), with a two-mode structure and a reaction-based concept, is developed for accident modeling and safety defense identification. The AcciTree model is then integrated with the well-established human factors analysis and classification system(HFACS) to enhance both reliability of the graphic part and logicality of the taxonomic part for improving completeness of analysis. An associative hazard analysis technique is further put forward to extend analysis to factors outside accidents, to form extended safety requirements for proactive accident prevention. Two crash examples, a research flight demonstrator by our team and an industrial unmanned aircraft, illustrate that the integrated approach is effective for identifying more unsafe factors and safety requirements.     

中间相炭微球为炭源反应形成SiC陶瓷及其结构与性能

以中间相炭微球和SiC粉为原料,模压渗硅制备了反应形成SiC陶瓷.计算了制品各相含量随SiC粉掺量、渗硅温度和保温时间改变的变化规律,同时测试了制品性能,并通过SEM观察了制品表面形貌.计算结果表明,随SiC粉掺量的增加,硅化后制品Si和SiC相体积分数提高,C相体积分数降低;渗硅温度的提高可降低制品开气孔率和提高密度...     

果皮富氧气化的动力学研究

利用小型固定床式气化炉对果皮进行富氧气化的实验，本文采用均相反应气化模型详细介绍了果皮富氧气化的表征动力学模型的建立，求得了果皮富氧气化的动力学参数。最后比较发现氧气作气化剂时的动力学参数小于二氧化碳作气化剂时的参数，相对来讲采用富氧气化效果优于二氧化碳。