机械结构的模糊优化设计

本文阐述了机械结构模糊优化设计的必要性及方法，并以用于５５千瓦风力发电机组的ＮＧＷ９２型行星齿轮传动为例，说明这一现代设计方法的实施及优良设计特性。     

Asymmetric synthesis of four isomers of 2-C-trifluoromethylerythritol

Optically active 2-C-trifluoromethylerythritols, analogues of 2-C-methylerythritol, which is a key intermediate in the biosynthesis of isoprenoid with a mevalonate-independent route, were conveniently synthesized from 1,1,1-trifluoro-2,3-epoxypropane.     

Cavity-enhanced laser cooling of solid-state materials in a standing-wave cavity

We propose a new method to cool the yb^3＋-doped ZBLANP glass in a standing-wave cavity. There are two advantages of this cavity-enhanced technique： the pumping power is greatly enhanced and the absorption of the cooling material is greatly increased. We introduce the basic principle of the cavity-enhanced laser cooling and discuss the cooling effect of a solid-state material in a cavity. From the theoretical study, it is found that the laser cooling effect is strongly dependent on the reflectivity of the cavity mirrors, the length of the solid material, the surface scattering of the material, and so on. Some optimal parameters for efficient laser cooling are obtained.     

Fabrication of CdSe composite by using the amphiphilic block copolymer as template

CdSe nanoparticles of improved stability against aggregation were synthesized by using amphiphilic block copolymer polyacrylonitrile-block-poly(ethylene glycol)-block-polyacrylonitrile (PAN-b-PEG-b-PAN, PEA). The products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopic (HRTEM). The optical properties were characterized by UV-vis spectrophotometer and the room temperature photoluminescence (PL). The results revealed that the CdSe nanoparticles have been uniformly distributed throughout the copolymer with diameters of 6-7 nm and the produced novel hybrid nanocomposites displayed obviously quantum size effects and interesting fluorescence features. FTIR results provided the information on the interaction between the copolymer and the nanoparticles. The TGA revealed that the thermal property of the copolymer enhanced due to the interaction of the nanoparticles and the groups of the copolymer.     

Channel coordination under fairness concerns and nonlinear demand

The supply chain literature analyzing supplier–retailer contracts and channel coordination has typically focused on profit or revenue maximization as the members’ sole objective. In such settings, it is well known that a simple wholesale price contract is not effective in coordinating the channel due to double marginalization. Recently, Cui et al. [Cui, T.H., Raju, J.S., Zhang, Z.J., 2007. Fairness and channel coordination. Management Science 53 (8) 1303–1314] introduced the members’ fairness concerns into channel coordination. Assuming a linear demand function, the authors show that a coordinating wholesale price contract can be designed when only the retailer or both parties are concerned about fairness. In this paper, we extend the authors’ results to other nonlinear demand functions that are commonly used in the literature. Our analysis reveals that, compared to the linear demand, the exponential demand function requires less stringent conditions to achieve coordination when only the retailer is fairness-concerned.     

Performance-Advantaged Stereoregular Recyclable Plastics Enabled by Aluminum-Catalytic Ring-Opening Polymerization of Dithiolactone

Chemically recyclable polymers that can depolymerize into their constituent monomers are attractive candidates to replace non-recyclable petroleum-derived plastics. However, the physical properties and mechanical strengths of depolymerizable polymers are commonly insufficient for practical applications. Here we demonstrate that by proper ligand design and modification, aluminum complexes can catalyse stereoretentive ring-opening polymerization of dithiolactone, yielding highly isotactic polythioesters with molar masses up to 45.5 kDa. This material can form crystalline stereocomplex with a T_m of 94.5 °C, and exhibits mechanical performances comparable to petroleum-based low density polyethylene. Exposure of the polythioester to aluminum precatalyst used to synthesized it resulted in depolymerization to pristine chiral dithiolactone. Experimental and computational studies suggest that aluminum complexes have appropriate binding affinity with sulfide propagating species, thereby avoiding catalyst poisoning and minimizing epimerization reactions, which has not been accessible using other metal catalysts. Overall, aluminum catalysis provides access to performance-advantaged stereoregular recyclable plastics as a promising alternative to petrochemical plastics, thus incentivizing improved plastic sustainability.     

Mechanistic Insight into Anion-Binding Catalytic Living Cationic Polymerization

Exploiting non-covalent interactions to catalyze challenging ionic polymerizations is an ambitious goal but is in its infancy. We recently demonstrated non-covalent anion-binding catalysis as an effective methodology to enable living cationic polymerization (LCP) of vinyl ethers in an environmentally benign manner. Here, we further elucidate the structure-reactivity relationships of the elaborately designed seleno-cyclodiphosph(V)azanes catalysts and the roles of anion-binding interactions by a combined theoretical DFT study and experimental study. The investigation suggests that the distinct cis-cyclodiphosph(V)azane framework combined with “selenium effect” and electron-withdrawing 3,5-(CF₃)₂-Phenyl substitution pattern in catalyst enables a critical contribution to accessing excellent stability, anion affinity and solubility under polymerization conditions. Thus, the catalyst could leverage anion-binding interactions to precisely control reversible and transient dormant-active species equilibrium, allowing it to dynamically bind, recognize and pre-organize propagating ionic species and monomer, thereby facilitating efficient chain propagation and minimizing irreversible chain transfer events under mild conditions. The more in-depth understanding of the mechanism for anion-binding catalytic LCP reported herein should help to guide future catalyst design and to extend this concept to broader polymerization systems where ionic species serve as crucial intermediates.     

绒毛奇蒿微量元素含量的测定

为提供合理利用绒毛奇蒿的科学依据,用火焰原子吸收光谱法首次测定了绒毛奇蒿地上不同部位中9种微量元素(Mn、Zn、Fe、Cu、Pb、Ni、Co、Cr、Cd)的含量,结果表明,绒毛奇蒿含有丰富的人体必需微量元素,有较高的开发利用价值。     

多目标模糊优化设计

多目标优化设计的函数曲面复杂并且缺乏分析理论，这使得多目标优化中的统一权法带有更多的盲目性。为解决这一难题，贴近度方法被用来分析统一权法的模糊学实质，并为多目标优化加权处理提供一有效的方法。     

α－混合过程条件密度的估计及其性质

本文在{Xr,t∈N）是一个严平稳过程的假设下,用核估计的方法对未来状态XN＋T的条件密度进行估计．在假设{Xt,t∈N）是α-混合过程的情况下,讨论了过程有限维密度核估计的期望与方差,以及过程条件密度核估计的偏及均方误差．在一定条件下,证明了估计的弱收敛性．