Bounding multi-stage stochastic programs from above

The purpose of this paper is to present general approaches for bounding some multi-stage stochastic programs from above. The results are based on restricting the solution set, such that the remaining multi-stage stochastic program is easy to solve. An example where the methods can be applied is presented.Supported in part by NATO Collaborative Research Grant No. 0785/87.     

三甲基膦和环氧乙烷的加成产物裂解反应机理的MNDO法研究

文中用ＭＮＤＯ方法研究了三甲基膦和环氧乙烷加成产物裂解反应机理     

用拓扑指数S_i研究碳氢化合物的沸点(Ⅲ)

定义了拓扑指数Ｓｉ（ｉ＝１，２，３，４），并选取包含双、三键、环及苯环的碳氢化合物为研究对象，计算了这些化合物的拓扑指数Ｓｉ，同时用Ｓｉ相关了它们的沸点．结果较文献值有所改善．并从Ｓｉ中筛选出了Ｓ     

二茂铁有机锡衍生物的13C,119Sn NMR研究

本文测定了几种二茂铁有机锡衍生物的¹¹⁹Sn,¹³C NMR谱。对其中几种衍生物的¹³C NMR谱进行了归属,从而进一步验证了这类化合物的结构。着重讨论了结构如化合物中取代基X的改变对¹¹⁹Sn化学位移的影响。并对结构如 类化合物N→Sn异侧配位的问题进行了讨论。     

ROOM TEMPERATURE LIGHT-THERMO-DETECTOR MADE OF HIGH-Tc SUPERCONDUCTOR

Based on the anisotropic Seebeck tensor coefficients, a light-thermo-radiation detector made of high-T_c superconductor (YBa₂Cu₃O_7-δ) was fabricated, which can function at room temperature. The induced voltaic signals at various modulation frequencies for radiation from He-Ne laser and from a 500 K black body were measured. The noise ratio for detecting He-Ne laser radiation and the D^* for black body were evaluated. Compared with bolometer made of high-T_c superconductor which functions at liquid nitrogen, and with pyroelectric detector, it was found that the advantages of this new device are that the device can work at room temperature with very low noise and very fast response. Although having a lower D^* value than that of bolometer for the present device construction, we point out the possibility and the direction for improving the D^* value, hence the promising prospect of this kind of device.     

The honeycomb network structure of poly[[[μ2‐1,3‐bis(1H‐benzimidazol‐2‐yl)benzene‐κ2N3:N3′](μ2‐terephthalato‐κ2O:O′)zinc(II)] ethanol solvate]

The terephthalate dianion and the bis(imidazolyl)benzene ligand of the title compound, {[Zn(C₈H₄O₄)(C₂₀H₁₄N₄)]·C₂H₆O}_n, each bridges two adjacent zinc centers, resulting in a layer‐type coordination polymer; the zinc center shows tetrahedral coordination. The disordered ethanol solvent molecules occupy the spaces between the layers and are hydrogen bonded to the layers. The two symmetry‐independent dianions lie on different inversion sites.     

Synthesis of grafted poly(p‐phenyleneethynylene) with energy donor–acceptor architecture via atom transfer radical polymerization: Towards nonaggregating and hole‐facilitating light‐emitting material

In this contribution, we demonstrate a new effective methodology for constructing highly efficient and durable poly(p‐phenyleneethynylene) (PPE) containing emissive material with nonaggregating and hole‐facilitating properties through the introduction of hole‐transporting blocks into the PPE system as the grafting coils as well as building the energy donor–acceptor architecture between the grafting coils and the PPE backbone. Poly(2‐(carbazol‐9‐yl)ethyl methacrylate) (PCzEMA), herein, is chosen as the hole‐transporting blocks, and incorporated into the PPE system as the grafting coils via atom transfer radical polymerization. The chemical structure of the resultant copolymer, PPE‐g‐PCzEMA, was characterized by NMR and gel permeation chromatography, showing that the desirable copolymer was obtained with the narrow polydispersity. The increased thermal stability of PPE‐g‐PCzEMA was confirmed by thermogravimetric analysis and differential scanning calorimetry along with its macroinitiator. The optoelectronic properties of this copolymer were studied in detail by ultraviolet‐visible absorption, photoluminescence emission and excitation spectra, and cyclic voltammogram (CV). The results indicate that PPE‐g‐PCzEMA exhibits the solid‐state luminescent property dominated by individual lumophores, and also the energy transfer process from the PCzEMA blocks to the PPE backbone with a relatively higher energy transfer efficiency in the solid‐state compared to that of the solution state. Additionally, the hole‐injection property is greatly facilitated due to the presence of PCzEMA, as confirmed by CV profiles. All these data indicate that PPE‐g‐PCzEMA is a good candidate for use in optoelectronic devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3776–3787, 2007     

Shape-controlled synthesis of nanocrystalline titania at low temperature

The interesting shape (shuttle-like, sphere with needles, uniform particles) rutile titania were prepared by the hydrolysis of TiCl₄ in high acidic aqueous solution in the absence or presence of PEG-1000. PEG-1000 acted as dispersant, which could control the shape and size of the precipitate of titania. As a result, shuttle-like nanocrystalline appeared and the aggregation was improved with the increase of the amount of acid and the decrease of the concentration of TiCl₄ in the absence of PEG-1000. Uniform nanoparticles were obtained in the presence of PEG-1000 and the diameter of the particles decreased with increasing the amount of PEG-1000. This process simplification will lower production cost and make continuous process possible. The products were analyzed using X-ray diffractometer, transmission electron microscopy.     

SPE电极上Pt单组分及Pt-Au双组分还原态CO_2阳极剥离电化学氧化行为研究

采用循环伏安法，对ＳＰＥＰｔ电极以及ＳＰＥＡｕ－Ｐｔ电极上还原态ＣＯ２的电化学氧化行为研究表明，此类电极的电化学特性与光滑Ｐｔ电极一致：ＣＯ２在氢原子吸附电位区０～２５０ｍＶ（ｖｓ．ＲＨＥ）处，可与电极上化学吸附的氢反应，生成还原态的ＣＯ２，通过线性扫描，还原态ＣＯ２即发生一不可逆电化学氧化过程（阳极剥离）．在ＳＰＥＰｔ系列及ＳＰＥＡｕ－Ｐｔ系列上ＣＯ２的电化学行为表明，当ＳＰＥＰｔ系列上Ｐｔ的载量为２．５ｍＬ的０．０１ｍｏｌ·Ｌ－１Ｈ２ＰｔＣｌ６的Ｐｔ时，对还原态ＣＯ２的电催化活性最好，当Ｐｔ的载量相同时，在ＳＰＥＡｕ－Ｐｔ上，催化剂对还原态ＣＯ２的电化学氧化行为比ＳＰＥＰｔ电极更强，这是由于预先沉积的Ａｕ对后沉积的Ｐｔ有调制作用．     

基于线性耦合下混沌系统的同步条件

将混沌同步问题用精确的数学语言给予描述，通过数学分析将其转化为微分方程组的稳定性问题.以Lorenz系统族的Chen氏系统作为典型系统，在线性耦合下分析系统参数，得到了系统达到同步时的充分条件，且在理论上加以证明.结合该条件，提出了一种确定耦合系数的方法.最后用仿真实验验证了该方法的正确性，并验证了在不同耦合方式和参考系统的情况下定理的有效性. 关键词： 混沌同步 耦合 稳定性