混凝土断裂面的实验研究

根据激光三角测量物体表面的原理,研制了可对混凝土的断裂面进行三维轮廓重构的实验装置 ,同时用数字图像分析仪测定了断裂面粗集料的信息。在此基础上,提出了可利用断裂面分数维和粗集料的拉断概率两个参数表征断裂面的特征以及它们的测定和计算方法。研究了混凝土组成材料对断裂面参数的影响和断裂面参数与混凝土力学性能的关系。采用断裂面分数维确定了更为精确的混凝土断裂能测定值。探讨了根据上述结果进行混凝土改性的可能性。

图像分析技术在混凝土断裂面研究中的应用

本文将先进的数值图像分析技术应用于破坏后混凝土断裂面的分析中，提出表征断裂面上粗集料破坏方式的参数——粗集料拉断概率的定义，并以不同强度等级、不同粗集料粒径的混凝土试件断裂面为例，探讨了粗集料拉断概率与混凝土强度和粗集料粒径的关系。初步的研究结果表明：混凝土强度越高，粗集料拉断率越大；在相同的混凝土强度下，粗集料粒径越大，粗集料拉断概率越大。

Power Allocation for Energy Harvesting in Wireless Body Area Networks

Wireless Body Area Networks(WBANs) are expected to achieve high reliable communications among a large number of sensors.The outage probability can be used to measure the reliability of the WBAN.In this paper,we optimize the outage probability with the harvested energy as constraints.Firstly,the optimal transmit power of the sensor is obtained while considering a single link between an access point(AP) located on the waist and a sensor attached on the wrist over the Rayleigh fading channel.Secondly,an optimization problem is formed to minimize the outage probability.Finally,we convert the non-convex optimization problem into convex solved by the Lagrange multiplier method.Simulations show that the optimization problem is solvable.The outage probability is optimized by performing power allocation at the sensor.And our proposed algorithm achieves minimizing the outage probability when the sensor uses energy harvesting.We also demonstrate that the average outage probability is reduced with the increase of the harvested energy.