不确定信息下的评估指标权重配置方法

为了解决在数据不确定条件下极大熵权重配置模型找寻最优权重的问题,引入云模型将具有随机性和模糊性的数据转换为定性的数字特征。以此为基础在逼近理想解排序方法架构下定义了正负理想解,基于改进的欧氏距离设计了正负向距离,提出了多评估对象相对能力量化模型,并在极大熵准则下构建了新的权重配置模型,使得评估对象相对能力大小排序的专家知识得到充分运用。通过分析采用了模拟退火算法实现最优指标权重的搜寻,解决了原先算法模型不能应用于非凸优化情形的问题,进而给出科学合理的权重配置方案。仿真实例表明,在多次迭代后找寻到最优权重熵为1.377 7,满足要求,证明了所提算法的有效性。     

Multi-Stage Phase-Segregation of Mixed Halide Perovskites under Illumination: A Quantitative Comparison of Experimental Observations and Thermodynamic Models

Photo- and charge-carrier-induced ion migration is a major challenge when utilizing metal halide perovskite semiconductors for optoelectronic applications. For mixed iodide/bromide perovskites, the compositional instability due to light- or electrical bias induced phase-segregation restricts the exploitation of the entire bandgap range. Previous experimental and theoretical work suggests that excited states or charge carriers trigger the process, but the exact mechanism is still under debate. To identify the mechanism and cause of light-induced phase-segregation phenomena, the full compositional range of methylammonium lead bromide/iodide samples are investigated, MAPb(Br_xI_1-x)₃ with x = 0…1, by simultaneous in situ X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy during illumination. The quantitative comparison of composition-dependent in situ XRD and PL shows that at excitation densities of 1 sun, only the initial stage of photo-segregation is rationalized with the previously established thermodynamic models. However, a progression of the phase segregation is observed that is rationalized by considering long-lived accumulative photo-induced material alterations. It is suggested that (additional) photo-induced defects, possibly halide vacancies and interstitials, need to be considered to fully rationalize light-induced phase segregation and anticipate the findings to provide crucial insight for the development of more sophisticated models.     

溅射法制备n型碲化镉薄膜的光电化学特性研究

采用溅射法制备了n型碲化镉薄膜。研究了不同沉积时间制备的n型碲化镉薄膜的形貌、结构和光学性质,以及薄膜厚度和退火工艺对n型碲化镉薄膜光电化学特性的影响。实验结果表明,溅射时间为25 min的碲化镉薄膜具有较好的PEC性能。退火工艺可以提高沉积的n型碲化镉薄膜的光电化学性能。当用饱和氯化镉溶液涂覆碲化镉薄膜并在真空中400 ℃退火时,n型碲化镉薄膜的光电化学性能最佳,光电流达到301 μA/cm²。     

Nonstationary Markov chains and convergence of the annealing algorithm

We study the asymptotic behavior as timet + of certain nonstationary Markov chains, and prove the convergence of the annealing algorithm in Monte Carlo simulations. We find that in the limitt + , a nonstationary Markov chain may exhibit phase transitions. Nonstationary Markov chains in general, and the annealing algorithm in particular, lead to biased estimators for the expectation values of the process. We compute the leading terms in the bias and the variance of the sample-means estimator. We find that the annealing algorithm converges if the temperatureT(t) goes to zero no faster thanC/log(t/t ₀) ast+, with a computable constantC andt ₀ the initial time. The bias and the variance of the sample-means estimator in the annealing algorithm go to zero likeO(t^–1+) for some 0<1, with =0 only in very special circumstances. Our results concerning the convergence of the annealing algorithm, and the rate of convergence to zero of the bias and the variance of the sample-means estimator, provide a rigorous procedure for choosing the optimal annealing schedule. This optimal choice reflects the competition between two physical effects: (a) The adiabatic effect, whereby if the temperature is loweredtoo abruptly the system may end up not in a ground state but in a nearby metastable state, and (b) the super-cooling effect, whereby if the temperature is loweredtoo slowly the system will indeed approach the ground state(s) but may do so extremely slowly.     

等离子体引发原位聚合制备凹凸棒土/聚苯乙烯纳米复合物

用阳离子表面活性剂处理凹凸棒土（Attapulgite),通过超声分散的方法将其均匀分散到苯乙烯单体中，并采用等离子体引发的方法制备出凹凸棒土／聚苯乙烯纳米复合物。通过透射电子显微镜（TEM）和X－射线衍射（XRD）观察了凹凸棒土及其纳米复合物的微观结构。对复合物的GPC测试表明，采用等离子体引发聚合反应可以显著提高树脂的分子量。XRD结果表明聚苯乙烯不是嵌入到凹凸棒土的层间，而是通过离子吸附接枝在凹凸棒土的棒状晶束上。     

烯烃氢甲酰化催化剂活性物种的原位1H NMR研究

The rhodium-phosphine complex catalyst Rh(CO)(acac)(PPh3)(Ⅰ) for 1-hexene hydroformylation was studied under the following reaction conditions: CO/H2=1(mole rate), pressure 1.0 MPa, temperature 25-120℃, by using the pressurized in-situ 1H NMR technique. Experimental results indicated that the formation of a rhodium hydride complex from (Ⅰ) began at room temperature and its amount increased with increasing of reaction temperature. This intermediate complex began to decompose at 100℃ and disapeared completely at 120℃. The intensity change of the proton signal was parallel to catalytical activity in hydroformylation of olefins. Under pure CO pressure the proton signal of Ph-H bond was not observed. There was a 0.2 ppm difference in proton chemical shifts of Rh-H bond under pure H2 pressure and under H2+CO pressure. The results showed that the rhodium-hydride carbonyl complex is the active intermediate in the industrial hydroformylation process.     

热处理对Nylon—11结构的影响

对不同温度热处理过的Nylon－11样品，采用广角X射线衍射（WAXD），根据X射线衍射强度理论，用多重峰图解分峰方法研究了Nylon－11结构的变化，并导出了计算Nylon－11结晶度的公式．所得结果与密度法、DSC法进行了比较．同时也给出了Nylon－11的有关热力学参数，     

CoTPP电化学催化原溴代环己烷的机理

以电化学循环伏安、现场ＥＳＲ电化学以及现场薄层电化学方法研究了电生Ｃｏ（Ｉ）ＴＰＰ与溴代五己烷的反机制。在ＤＭＦ中，Ｃｏ（Ⅱ）／Ｃｏ（Ⅰ）的氧化还原有明显的催化溴代环己烷还原的特片，反现场有自由基生成，反应产物之一是Ｃｏ－Ｃ键化合物，可以在１．３０Ｖ（ＳＣＥ）－电子还原，当存在ＣＨ２－ＣＨＣＮ时，。生成另一种Ｃｏ－Ｃ键化合物，该化合物在－１．１０Ｖ（ＳＣＥ）处一电子还原，证明溴代环己烷与Ｃｏ（Ｉ）     

Thermal behaviour of advanced composite materials based on SiC fibres

Emanation thermal analysis (ETA) was used for characterization of thermal behaviour of SiC_f/SiC composites on heating in argon and air, respectively. Effect of gas environment (argon, air) and helium ions implantation on the microstructure development of the SiC_f/SiC composite prepared by chemical vapour infiltration (CVI) from Nicalon CG fibres was investigated under in situ conditions of heating. The annealing of near surface structure irregularities was observed in the range 280-700°C and evaluated by means of the mathematical model, assuming that the structure irregularities served as diffusion paths for radon. The ETA reflected the formation of amorphous silica and its subsequent crystallization to crystoballite. Morphology of the SiC_f/SiC samples before and after the heat treatments was characterized by means of SEM. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photocatalytic Reduction of NO with C2H6 on a Hollandite-Type Catalyst

The photocatalytic reduction of nitrogen monoxide (NO) with ethane on the hollandite type catalyst (K₂Ga₂Sn₆O₁₆KGSO) was investigated. Using a closed-gas circulating system equipped with a Q-MASS detector and in-situ diffuse reflectance FT-IR spectroscopy. The reactant gases of NO and ¹³C₂H₆ decreased with the increasing irradiation time. In contrast, the N₂ yield increased proportionally to the conversion of ¹³C₂H₆. Nitrogen oxides such as N₂O did not reach their detectable levels. The NO adsorbed on KGSO was found to change to its activated species by UV irradiation. The oxidized products of C₂H₆ such as CH₃CHO increased in proportion to the reaction time. The present results strongly suggest that KGSO has remarkable photocatalytic activity for the reduction of NO with C₂H₆.