沥青混合料抗车辙性能的分形描述方法

为了准确模拟沥青混合料抗车辙性能, 采用分形理论分析了沥青混合料微观结构, 研究了粗细集料不同级配分形维数对沥青混合料抗车辙性能的影响, 并根据级配分形维数公式计算了沥青混合料的分形值, 进行了沥青混合料车辙试验和微观结构的电子扫描。分析结果表明: 4.75 mm通过率是集料尺度的分界点, 集料分形维数与抗车辙性能有一致相关性, 分形值越大, 抗车辙能力越高; 根据路用性能设计集料级配可以定量地分析沥青混合料的级配差异和路面性能, 及路面微观结构与宏观路用性能的关系。     

Geometrical design of blade＇s surface and boundary control of Navier-Stokes equations

In this article a new principle of geometric design for blade＇s surface of an impeller is provided. This is an optimal control problem for the boundary geometric shape of flow and the control variable is the surface of the blade. We give a minimal functional depending on the geometry of the blade＇s surface and such that the flow＇s loss achieves minimum. The existence of the solution of the optimal control problem is proved and the Euler-Lagrange equations for the surface of the blade are derived. In addition, under a new curvilinear coordinate system, the flow domain between the two blades becomes a fixed hexahedron, and the surface as a mapping from a bounded domain in R2 into R3 , is explicitly appearing in the objective functional. The Navier-Stokes equations, which include the mapping in their coefficients, can be computed by using operator splitting algorithm. Furthermore, derivatives of the solution of Navier- Stokes equations with respect to the mapping satisfy linearized Navier-Stokes equations which can be solved by using operator splitting algorithms too. Hence, a conjugate gradient method can be used to solve the optimal control problem.     

Study of the mechanism on the apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase

Objective To investigate the mechanisms of apoptosis induced in Human leukemia cell line K562 by the combination of indole-3-acetic acid and horseradish peroxidase. Methods Human leukemia cell line K562 were exposed to indole-3-acetic acid （IAA） at 20, 40, 60, 80 or 100 mol/L and horseradish peroxidase（HRP） at 1.2 g/mL for varying times. MTT assay was applied to detect the cell proliferation. Flow cytometry was performed to detect the arrest of cell cycle. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） assay was used to measure apoptosis. 2, 7-dichlorofluorescin diacetate （DCFH-DA） uptake was measured to determine free radical by confocal microscope. Content of malondiadehyde （MDA） and activity of superoxide dismutase （SOD） were measured by biochemical methods. Results IAA/HRP initiated growth inhibition of K562 cells in a dose- and time-dependent manner. Flow cytometry revealed that cell cycle arrested at G1/G0 after 24 hours treatment. After 72 hours treatment, apoptotic rate of 100 mol/L IAA group increased to 43.9 %, which was 5 times that of control（P〈0.01）. Content of MDA and activity of SOD increased respectively in treatments compared with control. Meanwhile, IAA/HRP stimulated the formation of free radical, which was increased by IAA concentration-dependently. Conclusion The combination of IAAand HRP can inhibit the growth of Human leukemia cell line K562 in vitro by inducing apoptosis which is associated with the increase of free radical. The combination of IAA and HRP might be a promising chemopreventive and chemotherapeutic agent against human leukemia.     

乌龙江大桥无覆盖层河床的钻孔平台设计

介绍在水深流急、潮位变化大、无覆盖层的深水中的基础施工平台设计,平台的稳定、精确定位、安全渡汛抗台是平台设计和施工的关键因素。     

Improved algorithm for distributed localization in wireless sensor networks

Many sensor network applications require location awareness,but it is often too expensive to equip a global positioning system(GPS) receiver for each network node.Hence,localization schemes for sensor networks typically use a small number of seed nodes that know their locations and protocols whereby other nodes estimate their locations from the messages they receive.For the inherent shortcomings of general particle filter(the sequential Monte Carlo method) this paper introduces particle swarm optimization a...     

汽车缓速制动装置的种类及特点

汽车上的缓速制动装置,根据工作原理不同,可分为发动机排气制动装置,电、磁式缓速器和液力缓速器等几种形式。     

桥梁橡胶支座疲劳损伤的初步研究

系统地对公路桥梁板式橡胶支座在容许荷载作用下进行了试验研究,根据橡胶支座内部橡胶与钢板结合部位的应力集中特点,分析了橡胶支座裂纹萌生的扩展情况,初步建立了简单的损伤模型,并根据该模型预测了橡胶支座损伤发展的趋势。     

特重车通过大跨石拱桥计算模型对比分析及试验验证

在对一重达376.7 t的特重车能否安全通过一主跨40 m的既有石拱桥进行安全评定时,针对石拱桥建立了两种实体分析模型:一为不考虑拱上填料、侧墙影响仅考虑拱上建筑与主拱联合作用的实体模型一;另一为考虑拱上填料、侧墙与主拱联合作用的较符合实桥实际情况的实体模型二.通过两种实体模型下的特重车过桥安全验算发现,采用计算模型二所有断面抗力均满足要求,而模型一的拱脚断面抗力不满足要求.在对比模型一、二在特重车下作用的挠度、应力结果后发现拱上填料、侧墙对结构的纵向空间整体工作性能影响较大.不考虑填料与侧墙的实体模型一相对于模型二的纵向刚度联系较弱,在荷载作用下的局部效应明显,从而揭示了实体模型一拱脚截面抗力效应不能满足规范要求的原因.通过荷载试验验证了采用实体模型二与实桥实际情况较为接近,而采用实体模型一的验算结果偏于保守.     

抗裂水泥稳定碎石在南京绕越高速东南段中的应用

抗裂水稳嵌挤能力强、整体强度高、收缩系数较小、抗裂性较好,能有效控制裂缝的产生。为解决水稳基层反射裂缝较高的问题,结合绕越高速抗裂型水泥稳定碎石施工,通过强度检验、加强关键的施工环节的控制、优化骨架密实水泥稳定碎石的级配设计等措施,有效降低了裂缝的数量。     

隧道火灾作用下水泥路面瞬态温度场计算方法

隧道发生火灾时水泥路面板内升温迅速,温度梯度较大,采用数值方法求解路面热传导偏微分方程易导致数值解振荡、计算结果失真,且过程繁琐.根据火灾下水泥混凝土热工参数变化规律及傅里叶余弦变换,推导了隧道火灾下路面内温度场的理论计算公式,并与通用有限元软件计算结果进行了比较.结果表明,推导公式可用于计算连续时间内路面板不同位置的温度分布,较好解决了数值方法求解路面瞬态温度场时数值解振荡、不连续的问题,提高了计算精度,且路面内温度场变化规律呈明显的抛物线型态势,与一维热传导微分方程的物理意义吻合较好.因此,推导公式求解火灾下路面结构瞬态温度场具有更好的适用性.