Identification of discrete chaotic maps with singular points

We investigate the ability of artificial neural networks to reconstruct discrete chaotic maps with singular points. We use as a simple test model the Cusp map. We compare the traditional Multilayer Perceptron, the Chebyshev Neural Network and the Wavelet Neural Network. The numerical scheme for the accurate determination of a singular point is also developed. We show that combining a neural network with the numerical algorithm for the determination of the singular point we are able to accurately approximate discrete chaotic maps with singularities

Selective Oxidation of 1,2-propane Glycol to Methylglyoxal: the Preparation of Ag/ZrO2 Catalysts by Biosynthesis Methods

丙酮醛（MGX）是一种重要的有机合成中间体，主要用作药物中间体，也广泛用于制备农药、食品添加剂等。丙酮醛通过与甲醛、氨等反应可以制得医药中间体4-甲基咪唑，还可以通过歧化反应制得用途广泛的乳酸。近年来随着咪唑以及呋喃酮等香料需求的增加，丙酮醛的需求量也日益增加，但它的天然存在量很少，而国内丙酮醛的生产起步晚，且规模较小。另外，丙酮醛的传统制备方法中所采用的催化剂多为电解银催化剂，电解银催化剂在反应温度低于500℃时活性不够，产物中有较多副产物羟基丙酮，而在高于500℃时，银微晶在高温条件下容易快速团聚导致催化活性下降。因此探索和深入研究在低温条件下具有高催化性能的催化剂，是丙酮醛实现经济、“绿...As an important organic intermediate, methylglyoxal(MGX) is mainly used as drug intermediates, and also has important applications in agricultural pesticide, food additives and so on. MGX can react with formaldehyde and ammonia to produce imidazole, which is a kind of drug intermediates. In addition, lactic acid can be produced by disproportionation reaction of MGX. Recently, the demand for MGX in...学位：工学硕士院系专业：化学化工学院化学工程与生物工程系_工业催化学号：2062007115090

Self-Assembly of Coordination Polymers

近年来，配位聚合物的自组装研究备受关注。它们在非线性光学、分子磁体、气体吸附、荧光等新型材料以及分子识别、多相催化等领域显示出诱人的应用前景。其中，热点课题—手性配位聚合物自发拆分现象的研究不但对于探讨生命同手性起源具有重要意义，而且在手性识别和不对称催化领域有着潜在的应用价值。本文首次合成了两种含有21螺旋链结构的配位聚合物[Ag(pyta)]n(1)和[Ag(prta)]n(2)。晶体结构分析结果表明，1和2中的银离子都是扭曲的四面体配位，pyta-和prta-均贡献出其N-O-S配位原子，其配位模式都是在文献中罕见的。所不同的是pyta-为四齿配体，化合物1为二维结构，产物是外消旋的配位...Self－assembly of coordination polymers has attracted much attention because of their remarkable applications to various fields such as nonlinear optical (NLO) materials, molecular magnets, gas absorption, fluorescent materials, as well as heterogeneous catalysis. Recently, the spontaneous resolution of chiral coordination polymers has become one of the hottest topics discussed by scientists from d...学位：理学硕士院系专业：化学化工学院化学系_无机化学学号：20012500

Very high frequency gravitational wave background in the universe

Astrophysical sources of high frequency gravitational radiation are considered in association with a new interest to very sensitive HFGW receivers required for the laboratory GW Hertz experiment. A special attention is paid to the phenomenon of primordial black holes evaporation. They act like black body to all kinds of radiation, including gravitons, and, therefore, emit an equilibrium spectrum of gravitons during its evaporation. Limit on the density of high frequency gravitons in the Universe is obtained, and possibilities of their detection are briefly discussed.Comment: 14 page