Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler

The influence of the electron beam modification of a dual‐phase filler on the dynamic mechanical properties of styrene‐butadiene rubber (SBR) is investigated in the presence and absence of trimethylol propane triacrylate or triethoxysilylpropyltetrasulfide. Electron beam modification of the filler results in reduction of the tan δ at 70°C, a parameter for rolling resistance, and an increase in the tan δ at 0°C, a parameter for wet skid resistance of SBR vulcanizates. These modified fillers give significantly better overall performance in comparison with the control dual‐phase filler. This variation in properties is explained in terms of filler parameters such as the filler structure that leads to rubber occlusion and filler networking. These results are further corroborated using the master curves obtained by the time–temperature superposition principle. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2992–3004, 2003     

基于未知环境状态新定义及知识启发的机器人导航Q学习算法

由于强大的自主学习能力, 强化学习方法逐渐成为机器人导航问题的研究热点, 但是复杂的未知环境对算法的运行效率和收敛速度提出了考验。提出一种新的机器人导航Q学习算法, 首先用三个离散的变量来定义环境状态空间, 然后分别设计了两部分奖赏函数, 结合对导航达到目标有利的知识来启发引导机器人的学习过程。实验在Simbad仿真平台上进行, 结果表明本文提出的算法很好地完成了机器人在未知环境中的导航任务, 收敛性能也有其优越性。     

SiC晶须增强陶瓷基复合材料的研究

用不同的Al_2O_3粉料,采用SiC晶须补强以及加入第三相SiC粒子弥散增韧的方式,研究了SiC晶须Al_2O_3基复合材料的力学性能,得到强度σ_f=780MPa,K_(Ic)=7.6MPa·m~(1/2)的结果。通过不同的分敌途径,对晶须分散效果进行了实验观察和探讨;并讨论了晶须的分散均匀性对力学性能的影响。同时,就晶须团聚体在增韧过程中所起的作用提出了一种新的、可能的增韧机制,合理地解释了实验结果。最后,就三元复合系统中晶须补强和弥散增韧两种途径的迭加效果进行了讨论。     

Average mixing torque,tensile and impact properties,and thermal stability of poly(vinyl chloride)/sawdust composites with different silane coupling agents

Unique explanations are given to describe changes in the mixing torque and tensile and impact properties of poly(vinyl chloride) (PVC)/wood sawdust composites affected by various types and concentrations of silane coupling agents. Concentrations of 0.5–1.0 and 1.5 wt % coupling agent are recommended for the optimization of the tensile and impact properties of the composites, respectively. Changes in the tensile and impact properties of the composites with a low sawdust content were more sensitive to the addition of silane coupling agents than those with a high sawdust content. KBM603 was suitable for improving the tensile properties, whereas KBE603 is recommended for high impact resistance of the composites. The differences in the mechanical and thermal properties of the PVC/sawdust composites were dependent on the characteristics of the functional groups in the silane coupling agents used, such as hydrophilic level, number of functional groups, self‐condensation reaction, and effectiveness of the hydrolysis reaction. Silane coupling agents above 1.0 wt % resulted in an increase in polyene sequences in the PVC structure. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 213–221, 2005     

Properties of lightweight expanded polystyrene concrete reinforced with steel fiber

Expanded polystyrene (EPS) concrete is a lightweight, low strength material with good energy-absorbing characteristics. However, due to the light weight of EPS beads and their hydrophobic surface, EPS concrete is prone to segregation during casting, which results in poor workability and lower strength. In this study, a premix method similar to the ‘sand-wrapping’ technique was utilized to make EPS concrete. Its mechanical properties were investigated as well. The research showed that EPS concrete with a density of 800-1800 kg/m³ and a compressive strength of 10-25 MPa can be made by partially replacing coarse and fine aggregate by EPS beads. Fine silica fume greatly improved the bond between the EPS beads and cement paste and increased the compressive strength of EPS concrete. In addition, adding steel fiber significantly improved the drying shrinkage.     

边坡锚固工程分析中的水平条分法

对目前中国规范推荐用于边坡加固计算的垂直条分传递系数法进行研究,发现将该方法用于边坡锚固受力分析时,不仅存在垂直条块与加固结构体（锚杆和锚索）相互交叉,而且计算得出的锚固力与加固体的实际锚固力存在偏差等缺陷。在相关资料提出的、用于加筋土稳定性分析的水平条分法基础上,结合边坡锚固工程的特点,将该水平条分法做进一步拓展,使其能适用于锚杆和锚索等边坡锚固工程的稳定性计算,并通过工程实例对拓展后的水平条分法进行了验证。     

基坑加固扰动引起地铁隧道隆起变形

针对如何控制上方基坑底部加固扰动引起下卧地铁隧道的变形、确保地铁安全运营的问题.结合上海市浦东新区东方路-张扬路地下立交工程,在考虑隧道等效刚度、施工卸荷以及加固抑制回弹的效果等因素的基础上,对上方搅拌桩施工扰动引起正在运营地铁隧道的竖向隆起变形进行了机理分析,推导出基于Winkler模型计算隧道竖向位移的方法并进行了理论计算.结果表明:上层加固扰动引起隧道的竖向位移是非常可观的,需引起足够重视.并将计算结果和实测数据进行了对比.在此研究基础上提出了一系列控制上层搅拌桩施工引起运营地铁隧道位移的施工方法.     

Nonlinear behavior of concrete beams with hybrid FRP and stainless steel reinforcements

The full-range behavior of partially bonded, together with partially prestressed concrete beams containing fiber reinforced polymer (FRP) tendons and stainless steel reinforcing bars was simulated using a simplified theoretical model. The model assumes that a section in the beam has a trilinear moment—curvature relationship characterized by three particular points, initial cracking of concrete, yielding of non-prestressed steel, and crushing of concrete or rupturing of prestressing tendons. Predictions from the model were compared with the limited available test data, and a reasonable agreement was obtained. A detailed parametric study of the behavior of the prestressed concrete beams with hybrid FRP and stainless steel reinforcements was conducted. It can be concluded that the deformability of the beam can be enhanced by increasing the ultimate compressive strain of concrete, unbonded length of tendon, percentage of compressive reinforcement and partial prestress ratio, and decreasing the effective prestress in tendons, and increasing in ultimate compressive strain of concrete is the most efficient one. The deformability of the beam is almost directly proportional to the concrete ultimate strain provided the failure mode is concrete crushing, even though the concrete ultimate strain has less influence on the load-carrying capacity. Foundation item: Project (50478502) supported by the National Natural Science Foundation of China     

关于P=7的Hardy不等式的一个加强改进

著名的英国数学家Hardy,证明了Hardy不等式对于任意的P存在着最佳常数（pp-1）p.之后,有许多学者对其进行了进一步的研究.近年来也有不少学者给出了P为某个定值时的加强改进.本文将给出P=7时,Hardy不等式的一个加强改进.     

硫酸钙晶须的制备及其在聚丙烯树脂中的应用

论述晶须及硫酸钙晶须的特性.以生石膏为原料,采用水热合成法,研究反应温度、反应时间、料浆浓度、Ca/Mg摩尔比等工艺条件对晶须形态的影响.在反应温度150℃、反应时间5 h、料浆质量分数为4%、n（Ca）/n（Mg）为10条件下,制备出了直径为1-5μm、长度为30-100μm的硫酸钙晶须.X-射线衍射分析表明,产品为无水硫酸钙晶须;同时对硫酸钙晶须的应用进行初步研究.根据实验结果,当晶须的填充量为5%时,聚丙烯的力学性能最佳,拉伸强度为39.18 MPa,断裂伸长率为125.41%.