基于形态滤波的心电信号去除基线漂移方法

去除基线漂移是心电信号预处理过程中的重要一步,常见方法具有计算量大、结果不佳等缺陷.本文运用形态学理论,结合心电信号特征,提出了基于形态学的心电信号基线漂移去除方法.该方法采用不同形状及尺寸的结构元素设计了两级形态学滤波器,分别对信号进行开闭、闭开级联组合运算.经验证,提出的方法能很好保持心电信号的特征形态,提高了信噪比,减小了均方差,有效去除了基线漂移噪声.     

Effects of adjacent bubble on spatiotemporal evolutions of mechanical stresses surrounding bubbles oscillating in tissues

The cavitation dynamics and mechanical stress in viscoelastic tissues, as the primary mechanisms of some ultrasound therapies, are extremely complex due to the interactions of cavitation bubble with adjacent bubbles and surrounding tissues. Therefore, the cavitation dynamics and resultant mechanical stress of two-interacting bubbles in the viscoelastic tissues are numerically investigated, especially focusing on the effects of the adjacent bubble. The results demonstrate that the mechanical stress is highly dependent on the bubble dynamics. The compressive stress and tensile stress are generated at the stage of bubble expansion and collapse stage, respectively. Furthermore, within the initial parameters examined in this paper, the effects of the adjacent bubble will distinctly suppress the radial expansion of the small bubble and consequently lead its associated stresses to decrease. Owing to the superimposition of two stress fields, the mechanical stresses surrounding the small bubble in the direction of the neighboring bubble are smaller than those in other directions. For two interacting cavitation bubbles, the suppression effects of the nearby bubble on both the cavitation dynamics and the stresses surrounding the small bubble increase as the ultrasound amplitude and the initial radius of the large bubble increase, whereas they decrease with the inter-bubble distance increasing. Moreover, increasing the tissue viscoelasticity will reduce the suppression effects of the nearby bubble, except in instances where the compressive stress and tensile stress first increase and then decrease with the tissue elasticity and viscosity increasing respectively. This study can provide a further understanding of the mechanisms of cavitation-associated mechanical damage to the adjacent tissues or cells.     

基于多目标人工鱼群算法的光疗LED照度优化研究

提高发光二极管（light emitting diode,LED）组成的光疗光源在照射平面上的照度均匀分布水平,对于光疗设备发展具有重要的价值。提出了一种基于多目标人工鱼群算法的光疗LED光源的照度优化方法。设计了2种不同组合模式的光疗LED光源阵列。结合多目标人工鱼群算法对光疗LED光源阵列组合数据进行优化,使光疗LED光源阵列的照度分布更加均匀。将优化设计后的光疗LED 光源芯片组合数据,导入光学仿真软件TracePro实现仿真验证,得到经优化的圆形光源排列的照度均匀程度较未优化圆形光源排列提升0.104,矩形光源排列的照度均匀程度较未优化矩形光源排列提升0.148。对比分析最终数据,验证了该优化方法是可行的,可以提高光疗LED光源的照度分布水平。