An element-free Galerkin method for ground penetrating radar numerical simulation

An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different from element-based numerical methods, this approach makes nodes free from the elemental restraint and avoids the explicit mesh discretization. First, we derived the boundary value problem for the 2D GPR simulation problems. Second, a penalty function approach and a boundary condition truncated method were used to enforce the essential and the absorbing boundary conditions, respectively. A three-layered GPR model was used to verify our element-free approach. The numerical solutions show that our solutions have an excellent agreement with solutions of a finite element method(FEM). Then, we used the EFGM to simulate one more complex model to show its capability and limitations. Simulation results show that one obvious advantage of EFGM is the absence of element mesh, which makes the method very flexible. Due to the use of MLS fitting, a key feature of EFM, is that both the dependent variable and its gradient are continuous and have high precision.

超声速气流中横向气体射流混合经验模型

为了获得适用于工程估算的射流穿透经验关系式,对射流中心迹线、穿透边界及喷注物展向分布特性进行模化处理,建立了描述超声速气流中横向气体射流混合经验模型,并通过系列实验观测结果对该模型有效性进行验证.结果表明：在较宽的动量比范围内（动量比为0.5~5.3）,该模型预测的射流中心迹线和穿透边界均与实验图像吻合较好,在射流中心迹线附近,该模型预测的喷注物摩尔分数与实验测量值相比误差在5%以内,精度优于现有模型.随着动量比的增大,在喷孔下游一定区域内,射流引起的反转旋涡对增强,导致该模型对展向摩尔分数分布的预估产生一定误差,表明该模型的适用范围与动量比和下游距离等因素相关.

施工经验：卷材板粉涂工艺

粉涂法是一种新工艺，分为粉末枪与粉末云两种技术，预处理后的基板外表面涂上粉末粘结剂，经感应加热到175℃，干燥，形成510um的干燥膜，再通过内水冷却不予考到40℃，这样处理好的基板穿过装在箱体里的粉涂装置、粉涂装置处在1个强大的静电场下，粉末旋转刷产生涂料粉末云，形成粉末云的固体涂料颗粒带有很高的电荷，其飞向高速运行的基板，产生足够大的边界穿透力，粉末颗粒便均匀地沉积在带钢表面。