Theoretical assessment of the catalytic (Pt/TiO2) oxidation of formaldehyde at ambient temperature

A recent article [C. Zhang, H. He, K. Tanaka, Catal. Commun. 6 (2005) 211] investigates the use of a Pt/TiO₂ catalyst for the oxidation of formaldehyde. The findings demonstrate nearly complete oxidation at ambient temperature (25 °C) for values of the surface velocity in the range 5–10 × 10⁴ h⁻¹ and a 45% destruction when using a surface velocity of 20 × 10⁴ h⁻¹.In the present communication, this oxidation was assessed by theoretical considerations of the reaction kinetics. The destruction efficiency was predicted using a first-order reaction rate expression, combined with different theoretical or semi-empirical equations for the intrinsic reaction rate constant. Predicted and experimental data are in fair agreement, thus validating the theoretical approach and confirming the experimental results.     

Solid polymer electrolytes. XI. Preparation,characterization and ionic conductivity of new plasticized polymer electrolytes based on chemical‐covalent polyether–siloxane hybrids

A new hybrid polymer electrolyte system based on chemical‐covalent polyether and siloxane phases is designed and prepared via the sol–gel approach and epoxide crosslinking. FT‐IR, ¹³C solid‐state NMR, and thermal analysis (differential scanning calorimetry (DSC) and TGA) are used to characterize the structure of these hybrids. These hybrid films are immersed into the liquid electrolyte (1M LiClO₄/propylene carbonate) to form plasticized polymer electrolytes. The effects of hybrid composition, liquid electrolyte content, and temperature on the ionic conductivity of hybrid electrolytes are investigated and discussed. DSC traces demonstrate the presence of two second‐order transitions for all the samples and show a significant change in the thermal events with the amount of absorbed LiClO₄/PC content. TGA results indicate these hybrid networks with excellent thermal stability. The EDS‐0.5 sample with a 75 wt % liquid electrolyte exhibits the ionic conductivity of 5.3 × 10^?3 S cm^?1 at 95°C and 1.4 × 10^?3 S cm^?1 at 15°C, in which the film shows homogenous and good mechanical strength as well as good chemical stability. In the plot of ionic conductivity and composition for these hybrids containing 45 wt % liquid electrolyte, the conductivity shows a maximum value corresponding to the sample with the weight ratio of GPTMS/PEGDE of 0.1. These obtained results are correlated and used to interpret the ion conduction behavior within the hybrid networks. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1000–1007, 2006     

NETEM阅读部分的真实性分析

从真实性的角度出发,利用Bachman的任务特征框架分析了NETEM阅读理解部分对考生交际语言能力的测试.分析表明,NETEM在输入材料方面有较高的真实性,任务涉及的语言能力的真实性也有很大的提高.但从输入与回答之间的关系看,个别题目未能体现交际语言能力的特点,仍有待改进.     

带缝空心R.C.剪力墙结构模型动力特性研究

为了研究带缝空心钢筋混凝土结构房屋的动力特性,进行了1∶3.0模型6层结构房屋的模态试验及拟动力试验,获得了结构的周期、振型、阻尼比、动力放大系数等动力特性参数。在试验研究的基础上,利用有限元分析软件ANSYS对结构模型进行了模态分析。研究结果表明,带缝空心钢筋混凝土剪力墙结构是一种介于框架结构和传统剪力墙结构之间的新型结构形式。试验结果与ANSYS模拟结果吻合较好,利用ANSYS软件进行仿真分析是测试结构动力特性的一种可靠方法。     

基于均衡接近度灰关联的Slope One算法

作为一种基于项目的协同过滤推荐算法,Slope One算法易于实现且高效。但由于Slope One算法未考虑用户相似性,导致其在处理涉及用户关系的个性化推荐任务时性能不高。针对以上问题,提出了改进的Slope One算法。提出一种均衡接近度灰关联分析方法计算用户之间的均衡接近度,利用均衡接近度度量用户间的相似程度,然后将均衡接近度值融入到Slope One算法中进行评分预测,在MovieLens和Epinions数据集下的对比实验表明,该算法具有更低的平均绝对误差（MAE）和均方根误差（RMSE）,提高了预测的准确度和推荐质量。     

波浪对圆柱外接圆弧型防波堤绕射的解析计算

在微幅波绕射理论的基础上,使用特征函数展开法,推导了圆柱外接圆弧型防波堤复合结构的水波绕射的解析解,并据此计算了该结构所受到的波浪载荷以及绕射波面分布。计算结果表明:与单一圆柱相比,外接圆弧型防波堤的存在可明显降低作用于圆柱的波浪载荷和圆柱表面的波浪爬高;采用外接堤表面密实或透空而内圆柱表面透空的结构形式可以取得圆柱防浪的较佳效果;结构透空系数、波浪入射角度、外接堤张角、外堤半径与水深比、水深与波长比等因素的变化对绕射波浪作用均存在一定影响。     

弧形短导航墙对船闸下游引航道内水流结构的影响

通过物理模型试验,结合理论分析,研究了在不同下游水深条件下,直导航墙长度L变化对船闸下游引航道保护长度的影响,并在此基础上研究了增设弧形短导航墙对水流结构的调整与影响。物理模型试验研究表明:直导航墙长度的增加有利于改善船闸引航道口门区的通航条件,但在达到一定长度之后,再增加直导航墙长度对引航道口门区水流结构的改善效果减弱;弧形短导航墙对改善下游引航道保护区域内水流结构有很好的效果,选用较小纵向参数a和较大横向参数b效果更好,但张角不宜过大。     

Numerical analysis of rainfall effects in external overburden dump

The effect of slope angle for external overburden dump in response to average and heavy rainfall has been analyzed using a two dimensional finite difference method of transient water flow through unsaturated–saturated soil. The external dump stability is evaluated for five geomaterial types on the basis of globally accepted safety factor analysis technique, based on shear strength reduction approach using finite difference method. The results obtained from the finite difference method of analysis indicate that the external dump with more than 30° slope angle is greatly influenced by the rainfall under the studied conditions for geomaterial 3, 4 and 5, whereas dumps with geomaterial 1 and 2 remain safe. The analysis shows that major slope failure is out of preview for the studied rainfall conditions.     

合肥新型城镇化发展模式探讨

我国城镇化正经历由量的扩张向质的提升转变,学术界和地方政府对新型城镇化进行了大量的理论研究和实践探索。从国家新型城镇化战略和合肥地位背景入手,对合肥城镇化建设现状格局进行分析,结合其他类似城市建设经验,从构建特大城市空间体系、合理发展大中城市、积极发展中心镇和新市镇、分层推进四个方面探讨合肥新型城镇化建设发展模式。