Fracture Toughness of Phenol Formaldehyde Composites: Pilot Study

A commercial phenol formaldehyde based resole thermosetting resin (Hexion “J2027L”) was filled with ceramic-based fillers (Envirospheres “slg”) to increase its strength and fracture toughness. By testing viscosity, strength, and fracture toughness at a range of filler addition levels, the optimal addition level of SLG was able to be determined in terms of workability, cost, and performance. It was found that the fracture toughness of this resin could be significantly increased through the addition of the slg filler. The results show that composite with 20% by weight of the slg produces the best balance between ease of casting and impact performance.     

Non-Line-of-Sight Localization in Multipath Environments

Location-based spatial queries (LBSQs) refer to spatial queries whose answers rely on the location of the inquirer. Efficient processing of LBSQs is of critical importance with the ever-increasing deployment and use of mobile technologies. We show that LBSQs have certain unique characteristics that the traditional spatial query processing in centralized databases does not address. For example, a significant challenge is presented by wireless broadcasting environments, which have excellent scalability but often exhibit high-latency database access. In this paper, we present a novel query processing technique that, though maintaining high scalability and accuracy, manages to reduce the latency considerably in answering LBSQs. Our approach is based on peer-to-peer sharing, which enables us to process queries without delay at a mobile host by using query results cached in its neighboring mobile peers. We demonstrate the feasibility of our approach through a probabilistic analysis, and we illustrate the appeal of our technique through extensive simulation results.     

A new model of turbulent fibre suspension and its application in the pipe flow

A new model of turbulent fibre suspension in pipe flow is developed by deriving the equations of Reynolds averaged Navier‐Stokes, turbulence kinetic energy and turbulence dissipation rate with the additional term of the fibres, and the equation of probability distribution function for mean fibre orientation. The equations are solved numerically. The numerical mean velocity is in agreement with the experimental data. The effects of Reynolds number, fibre concentration, and fibre aspect‐ratio on the mean velocity, turbulent kinetic energy and turbulent dissipation rate are analysed. The results show that the effect of Reynolds number on the flow behaviour is insignificant. The turbulent kinetic energy and turbulent dissipation rate increase with an increasing fibre concentration and fibre aspect‐ratio. © 2012 Canadian Society for Chemical Engineering     

虚拟环境中的彩色CCD摄像机校准

根据虚拟演播室的需要,利用图像识别技术和Tsai两步校准算法的思想,在VisualC++平台上编制了CCD摄像机的校准软件。首先利用仿真数据对校准算法进行检验和分析,指出其中的规律和问题。其次在真实的蓝色演播室环境中对摄像机进行校准,提出了特定的处理方法,得到了满意的非线性焦距变化曲线。最后,详细分析了图像处理精度和校准算法对校准结果的影响。