Interactions between defects and propagating hydrodynamic solitons

<正>This paper studies the hydrodynamic solitons propagating along a long trough with a defective bed.The slight deviation from the plane in the bed serves as the depth defects.Based on the perturbation method,it finds that the free surface wave is governed by a Korteweg-de Vries(KdV) equation with a defect term(KdVD).The numerical calculations show that,for a single-convexity localized defect,the propagating soliton is decelerated as it comes into the defect region,and it is accelerated back to its initial velocity as it leaves,which has a dipole effect.As a result, its displacement is lagged in contrast to the uninfluenced one.And an up-step defect makes the propagating soliton decelerate simply.The opposite influence will occur for a single-concavity localized defect and a down-step one.The defect-induced influence on propagating hydrodynamic solitons depends on the polarity of defects,which agrees with that on non-propagating ones.However,the involved dipole effect of the single localized defect is not displayed in non-propagating cases.     

自相似声压驱动下气泡的振动

单泡声致发光来自于气泡经过缓慢膨胀之后的急剧塌缩的过程,而这种急剧塌缩是高阶谐波振动的结果。基于线性叠加的思想,提出了自相似驱动的概念,即用与半径振动相似的声压来驱动气泡。数值模拟表明,自相似驱动声压能够有效地加剧气泡的塌缩过程。与正弦驱动比较,包含基波和二次谐波的自相似驱动显著地提高光辐射强度。这为多频最优化驱动提升发光强度提供了一个直观的物理图景,也给出了一种可用于实验的提升声致发光的方法。     

Temperature Effect on Single Bubble Sonoluminescence

Experiments of the temperature effect on single bubble sonoluminescence (SBSL) are performed with a mixture of water and anti-freeze.Since experiments of constant pressure (keeping sound pressure constant) are not feasible for a wide temperature range,experiments of constant luminance (keeping light intensity stable),which reflect pure sensitivity of SBSL to temperature,are investigated.The results show that lower temperature needs less pressure to obtain the same light intensity,which means that lower temperature is better for SBSL.Numerical calculations show a qualitative agreement with experiments.     

一种新型高发射效率的阳极短路IGBT

提出了一种新型的双发射短接的阳极短路IGBT结构,该结构有两个空穴放射区和二氧化硅阻挡层。首先,第二发射区可以增加空穴的发射效率同时阻止电子直接流向金属,增加了阳极上的电阻和电压,有效的抑制了负阻效应;另一方面,二氧化硅阻挡层使得大量电子聚集在阳极区附近,进一步降低了导通压降。结果表明：相对于传统NPT IGBT, NPN-IGBT和阳极短路IGBT,导通压降分别降低了10%, 17%, 30%。另外,这种阳极短路结构由于有一个电子通道,在关断过程中可以像阳极短路结构一样抽取过剩载流子,使得其关断时间很短,在同样的导通压降下关断,相对于传统NPT IGBT,NPN-IGBT和阳极短路IGBT,关断损耗分别降低了43.7%, 32%, 28%。这种新结构最终实现了导通压降和关断损耗之间很好的折中。     

BOSS系统高可靠性承载平台的设计

本文从系统集成的角度来阐述关键业务系统承载平台的部署及设计,描述广州有线BOSS系统具体的系统组成,对系统高可靠性进行了多方面的设计,以保障系统能够7×24小时全面支撑业务开展.     

孤立波在一维复合颗粒链中传播特性的模拟研究

采用分子动力学方法模拟研究了孤立波在重轻颗粒相间排列的一维复合颗粒链中的传播特性.结果发现,在轻重颗粒的质量比较大或较小时,散射作用较弱,颗粒的速度和孤立波的速度衰减较慢.在轻重颗粒的质量比为中等时,散射作用较强,颗粒的速度和孤立波的速度衰减较快.孤立波在通过重-轻颗粒界面时,存在有增速效应,可以提高孤立波的传播速度.并且,轻重颗粒的质量比越小增速效应越强.在散射作用和增速效应的共同作用下,改变轻重颗粒的质量比可以调控孤立波在重-轻颗粒链中的传播时间.