Evaluation of surface textures and skid resistance of pervious concrete pavement

Surface textures had long been recognized as primary factors to provide the skid resistance on pavements; however, no measurement of skid resistance on pervious concrete pavement with various surface texture parameters had been made. Fractal geometry was introduced in the present work to accurately simulate transect contour curves of pervious concrete specimens through fractal interpolation. It is proved that its fractal dimension (D) can be adopted to measure the skid resistance on pervious concrete pavement, overcoming the shortcomings of both macrotexture depth (DT ) and British portable pendulum number (NBP). Combined with Fujikawa-Koike tire/road contact model, the optimization method of all surface textures was recommended for designing and constructing excellently skid-resistant and noise-absorptive pervious concrete pavement. In addition, evaluating of the abrasion process and attenuation of the surface textures on concrete pavement slabs was also the focus of this work based on accelerated abrasion test. Results show that the surface textures on pervious concrete pavement slabs is extremely durable, compared to those on conventional grooved or exposed aggregate concrete pavement slabs.     

对沥青混凝土粘弹性力学性能及沥青混凝土防渗斜墙温度应力的研究

本文应用高聚物分子运动的学说,阐述了沥青混凝土材料的粘弹性力学行为。通过分析分子运动与温度和荷载作用时间的关系及其对沥青混凝土材料力学性能的影响情况得出:欲正确地研究和合理地使用水工沥青材料,应考虑其粘弹性特性。文中从我国现有的设备条件出发,依据线性粘弹性理论,通过对50余组试件进行拉伸和徐变试验,利用徐变柔量和松驰模量之间的转换,近似求得了反映沥青混凝土材料粘弹性力学性能的重要参数——不同温度下沥青混凝土的松驰模量,并视斜墙为粘弹性嵌固板,应用所测得的松驰模量,计算了北京市半城子水库沥青混凝土防渗斜墙的温度应力,其结果符合实际情况。本文的试验和计算结果,可供今后评定沥青混凝土防渗斜墙的抗裂性和进行配合比设计时参考使用。     

TM1300芯片的以太网通信接口的设计和实现

设计通过TM1300的PCI接口驱动以太网芯片。实现了一种以太网通信接口。该方案将擅长多媒体信号处理的TM1300和十分普及的以太网结合起来，可以方便地实现视频通信。文章对该方案的软件和硬件的设计要点进行了详细的介绍。并给出院 对模拟数据和实际视频压缩码流的传送实验结果。     

水泥窑灰-粉煤灰体系的水化与强度发展(英文)

研究了配合比与养护温度对水泥窑灰(cement kiln dust,CKD)—粉煤灰(fly ash,FA)净浆的水化与强度发展的影响。净浆采用5种不同的水泥窑灰与粉煤灰比例配制,部分试件添加硅酸盐水泥作添加剂。试件在24、38℃及50℃的条件下进行养护。采用热重分析与X射线衍射测试试件的水化产物。结果表明在50℃的养护条件下,75%CKD+25%FA与45%CKD+45%FA+10%OPC试件的28 d与56 d强度分别达到了100%OPC水泥净浆强度的70%与80%以上。CKD-FA体系中的主要结晶水化产物是钙矾石。无论CKD与FA比例多大,CKD-FA浆体中钙矾石的含量显著高于水泥净浆。CKD-FA体系中钙矾石在90d的龄期仍可保持稳定。     

双片TM1300视频采集卡的高速数据传递方案

介绍了一种基于双片TM1300的双路视频采集卡的高速数据传递方案。在分析了TM1300芯片的EVO、VI、PCI、SSI等外设接口特性的基础上，提出了用EVO与VI互联来实现双路视频采集卡中双片TM1300间高速数据传递的设计方案。其特点是实现简单，数据传送效率高，并采用CPLD芯片设计了EVO与VI的逻辑接口，通过MAX PLUSⅡ时序仿真验证了CPLD设计的正确性。