Double pull specimen more suitable for measuring bond-slip relationship of FRP-to-concrete interface

A new "conceptual" design named "double pull" specimen was proposed in order to measure the bond-slip (δ-τ) relationship of fiber reinforced polymer (FRP)-to-concrete interface more accurately. A finite element analysis (FEA) was performed for preliminarily evaluating the suitability of the proposed conceptual double pull specimen. Through the FEA, it was indicated that the FRP-to-concrete interface of the proposed conceptual specimen might subject to a much higher load level than that of the most commonly used simple shear specimen, showing a great potential for measuring δ-τ relationship more accurately. In the light of the conceptual specimen, a kind of "practical" double pull specimen was developed and proved to be more suitable for measuring δ-τ relationship through an exploratory experimental study with 20 specimens. Consequently, an experimental program with 10 double pull specimens was performed for measuring the ultimate slip δ_u which was difficult to capture by using the existing specimens. It is shown that the range of δ_u is 0.31-0.52 mm based on the test results. The suggestion for improving the measure method is also put forward.     

Progress in the Study on the Phase Equilibria of the CO2·H2O and CO2-HeO-NaCI Systems

To study the feasibility of CO2 geological sequestration,it is needed to understand the complicated mul- tiple-phase equilibrium and the densities of aqueous solution with CO2 and multi-ions under wide geological condi- tions（273.15—473.15K,0—60MPa）,which are also essential for designing separation equipments in chemical or oil-related industries.For this purpose,studies on the relevant phase equilibria and densities are reviewed and analyzed and the method to improve or modify the existing model is suggested in order to obtain more reliable predictions in a wide temperature and pressure range.Besides,three different models（the electrolyte non random two-liquid（ELECNRTL）,the electrolyte NRTL combining with Helgeson model（ENRTL-HG）,Pitzer activity coefficient model combining with Helgeson model（PITZ-HG））are used to calculate the vapor-liquid phase equilib- rium of CO2-H2O and CO2-H2O-NaCl systems.For CO2-H2O system,the calculation results agree with the experimental data very well at low and medium pressure（0—20MPa）,but there are great discrepancies above 20MPa.For the water content at 473.15K,the calculated results agree with the experimental data quite well.For the CO2-H2O-NaCl system,the PITZ-HG model show better results than ELECNRTL and ENRTL-HG models at the NaCl concentration of 0.52mol·L ^-1 .Bur for the NaCl concentration of 3.997mol·L ^-1 ,using the ELECNRTL and ENRTL-HG models gives better results than using the PITZ-HG model.It is shown that available experimental data and the thermodynamic calculations can satisfy the needs of the calculation of the sequestration capacity in the temperature and pressure range for disposal of CO2 in deep saline aquifers.More experimental data and more accurate thermodynamic calculations are needed in high temperature and pressure ranges（above 398.15K and 31.5MPa）.     

原位合成的介孔TiO2-B/锐钛微粒:改善的锂离子电池阳极材料（英文）

Mesoporous TiO2-B/anatase microparticles have been in-situ synthesized from K2Ti2O5 without template. The TiO2-B phase around the particle surface accelerates the diffusion of charges through the interface, while the anatase phase in the core maintains the capacity stability. The heterojunction interface between the main polymorph of anatase and the trace of TiO2-B exhibits promising lithium ion battery performance. This trace of 5%(by mass) TiO2-B determined by Raman spectra brings the first discharge capacity of this material to 247 mA·h·g?1, giving 20%improvement com-pared to the anatase counterpart. Stability testing at 1 C reveals that the capacity maintains at 171 mA·h·g?1, which is better than 162 mA·h·g?1 for single phase anatase or 159 mA·h·g?1 for TiO2-B. The mesoporous TiO2-B/anatase microparticles also show superior rate performance with 100 mA·h·g?1 at 40 C, increased by nearly 25%as compared to pure anatase. This opens a possibility of a general design route, which can be applied to other metal oxide electrode materials for rechargeable batteries and supercapacitors.     

钛酸钾晶须增韧尼龙66及其断面分形研究

钛酸钾晶须用弹性体表面改性后实现了对尼龙66的有效增韧,改性剂 氧树脂用量为晶须的1．5％（质量）时,复合体系的冲击强度比纯尼66提高132％,同时弯曲,拉伸强度分别提高55％和48％,采用显微图像灰度法,对晶须增韧尼龙进行了基于断面小岛周长－面积关系的分形研究,考察了小岛选取对断面分维数测量结果的影响,研究表明,测得的分维数随选取小岛的面积阈值增加而增大,面积阈值达500η^2(η为侧量码尺）后,分维数趋于稳定,晶须增韧尼龙的力学强度与材料断面分维数之间的变化规律一致,对于从材断断裂机制与断面形貌进行了解释。     

纳米TiO2与炭纤维协同填充PTFE复合材料的摩擦磨损性能

考察了不同含量的纳米二氧化钛对炭纤维/聚四氟乙烯复合材料摩擦磨损性能的影响,采用扫描电子显微镜、光学显微镜分析了磨损面、磨屑及对偶面转移膜形貌,并探讨了其磨损机理。结果表明,纳米TiO2与炭纤维能够很好地协同增强聚四氟乙烯,改变磨屑形成机理,有利于形成均匀致密的转移膜,明显提高CF/PTFE复合材料的耐磨性。当纳米TiO2含量为5%时,10?/PTFE复合材料表现出最佳的耐磨性,耐磨性又提高了2.77倍,而磨屑尺寸只有未加时的1/20。     

汽车制动抖动机理及改善研究

为分析DTV和悬架衬套刚度对制动抖动的影响,通过整车道路试验研究了制动抖动时频特征,基于快速傅里叶变换对DTV数据进行了频次分析,利用多体动力学方法计算了悬架系统模态。研究表明：制动抖动整车道路试验的振动加速度频谱具有阶次特征;DTV数据频次分析的频域成分以一次和二次DTV为主,这与制动抖动能量集中在一阶和二阶频带的特征吻合,降低频次DTV幅值对控制制动抖动的振源激励有重要作用;前悬纵向模态是制动激励被放大的原因,前下控制臂后点衬套侧向刚度越高,模态特征值越高,制动抖动程度越轻,合理匹配悬架衬套刚度能有效改善制动抖动。     

化工模拟图形输出系统GOCES

针对目前微机内存较小、科学计算的图形输出不便的现状，提出了将数据库与模拟软件分割、结合的方法，并利用GRAPHER绘图软件，制成了用FORTRAN77编写的化工计算和模拟的图形输出系统，该系统实现了物性数据库及热力学推算与化工单元过程模拟的连接，并将结果图形化，达到仅通过检索体系中存在的组份便能获得有关物性及相平衡的图形结果，进而结合操作条件获得有关模拟计算的图形结果的目的，同时可自动将计算、模拟结果根据需要在绘图仪或打印机上输出。     

微机在电导分析法中应用的研究

本文研究了微机在电导分析法中的应用。通过拟合十六个单一电解质水溶液体系电导与浓度的关系,采用直接测量电导分析法,便可确定这些二元溶液组成。利用微机作图,回归直线方程来求取电导滴定等当点,使得电导滴定法更为迅速、准确。作者进一步提出,将直接测量电导率法与电导滴定法相结合,借助微机处理实验数据,可以分析强电解质、水和有机溶剂三元溶液。     

介孔氧化钛晶须光催化降解发酵生产废水的研究

以水合氧化钛和K2CO3为原料合成了具有微米级形貌、较高比表面积和均匀孔径的介孔锐钛矿型TiO2晶须,研究了在波长为365 nm的紫外光下光催化降解初始COD为200 mg/L的发酵生产废水的COD变化。结果表明,在光解30 min后,废水COD降至85 mg/L,达到再利用要求;当加入TiO2晶须质量浓度为0.5 g/L时,光催化反应速度最大。     

利用自组装单分子膜对表面结构和性质的研究进展

以硅烷和硫醇两种体系为代表介绍了自组装单分子膜的结构和形成机理，指出自组装单分子膜具有单分子层性质和灵活的分子设计特性，综述了其作为表面结构和性质研究工具的最新进展。