Experimental investigations of enhanced glow based on a pulsed hollow-cathode discharge

In this work, the pulsed hollow cathode discharges at low pressure argon with an axial magnetic field were studied. The results indicate that the pulsed discharge is operated in an enhanced glow(EG) mode. Under the same conditions, the discharge current of the pulsed discharge is two or three orders higher than that of the direct current discharge. The spatial and temporal evolution of the light emission shows that, the current fluctuation at the rising edge of the pulse plays an important role for the EG discharge of pulsed hollow cathode, which forms a high-density, highcurrent and long-distance plasma column outside the cavity.     

含软弱夹层岩体爆破的夹层土运动特征试验研究

 以单孔台阶爆破为原型,进行含软弱夹层的混凝土模型爆破试验,利用高速摄像观测爆破过程中夹层土的运动状态,分析不同炮孔装药量、夹层土含水率和最小抵抗线条件下夹层土的运动特征及其变化规律。研究结果表明,利用高速摄影可以清晰地观测到距炮孔中心2～4 cm之后的夹层土的运动影像,从而证实爆破对紧邻炮孔的软弱夹层的推移作用;模型爆破时夹层土的最大运动速度可达450 m/s,并随着与爆心距离的增大,夹层土的运动速度大致呈线性降低,其降低幅度主要受夹层土含水率和炮孔装药量的影响;距炮孔相同距离处的夹层土运动速度和运动的最大距离均随装药量、含水率、最小抵抗线的增加而增大,且装药量对夹层土的最终推移距离起着主要作用。     

Boundary Effect of Planar Glow Dielectric Barrier Discharge and Its Influence on the Discharge Structure

The dielectric barrier discharge(DBD) in the glow regime in neon has been investigated by experiment and two-dimensional(2D) fluid modeling.The discharge was carried out in a planar DBD system with segmented-electrodes driven by square-wave voltage.The results show that the glow DBD originates in the center of the electrode and expands outward to the electrode edge during each half cycle of the voltage,forming a radial structure.The discharge decays firstly in the inner area but sustains longer in the edge area,showing a reversed discharge area.The discharge cannot completely cover the entire electrode surface,but remains a border of non- or weak discharge.The fluid modeling shows a similar result in agreement with the experiments.The simulations indicate that the electric field in the edge area is distorted due to the boundary effect so that the electric field and charge distribution are different from that in the inner part.The distorted field reduces the longitudinal component near the edge and causes the local field to be lower than that in the center,and hence makes the discharge behindhand.It also induces a transverse field that makes the discharge extend radially outward to the edge.The boundary effect plays an important role in the glow DBD structure.     

基于COMSOL的隧道地应力场反演

结合隧道区域构造环境及青藏高原地应力数据基础,文章利用犀牛、COMSOL等软件构建隧址区三维数值模型,采用应力边界试算法确定模型计算的加载条件,进行隧址区地应力场的三维数值反演分析,通过隧道切面计算云图及隧道轴线初始应力场展示了岩性复杂的长大深埋隧道初始地应力场分布规律。     

Nonlinear phenomena in dielectric barrier discharges: pattern,striation and chaos

The nonlinear phenomenon is very popular in dielectric barrier discharge (DBD) plasmas. There are at least three kinds of spatial and temporal nonlinear phenomena appearing synchronously or asynchronously in DBDs, i.e. self-organized patterns, striations and chaos. This paper describes the recent research and progress in understanding the nature of these nonlinear phenomena. Patterns are macroscopic structures with certain spatial and/or temporal periodicities generated through self- organization of microscopic parameters. The physics of patterns in DBDs is mainly associated with lateral dynamic behaviors or the lateral non-local effect of charged particles resulting in the lateral development or non-uniformity of discharge. Striations are ionization waves with unique properties determined by transport phenomena, ionization processes and electron kinetics in current-carrying plasmas. The physics of striations in DBDs is mainly associated with the advances in non-local electron kinetics in spatially inhomogeneous plasmas. Chaos is a kind of random and non-periodic phenomenon occurring in a determined dynamic system, following a series of certain rules while exhibiting random locomotion, and is regarded as an intrinsic and ubiquitous phenomenon in a nonlinear dynamic system. An evolution trajectory including period-doubling bifurcation to chaos was observed in DBDs or DBD-derived plasmas. In a common sense, it is believed that the formation of all the three nonlinear phenomena in a DBD system should be related to the non-local transversal and/or longitudinal dynamics of space charges (i.e. non-local effect) or the localized electric field interaction. Future work is still needed on the underlying physics and should be directed to pursuing the unification of these nonlinear phenomena in DBD.     

福建省第十四届大学生运动会跳绳比赛调研与分析

本文主要采用文献资料法、专家访谈法、现场观察与统计法、spss软件分析法,对福建省第十四届大学生运动会跳绳比赛数据进行调查分析,目的是推动跳绳比赛朝着健康、稳定的方向发展,有利于提高跳绳的技术水平。     

爆破作用下层间充填物运动规律的试验研究

通过对含层间充填土的混凝土模型爆破过程的高速摄像实验,观测爆破作用夹层充填土运动过程,发现爆炸作用下层间充填土的运动规律：距炮孔中心2～4 cm之后的层间充填土的运动速度可以分为3个阶段,即速度迅速降低、速度基本稳定和速度急速降至0;层间充填土运动速度随着药量的增加而增大,且药量大的层间充填土的速度降低段较宽、速度基本稳定段较窄,这为进一步研究爆破对岩体夹层充填物的作用机理及其稳定性研究提供了依据。     

填充介质对电晕放电特性的影响

为了研究填充介质对电晕放电的影响,本文采用针-板放电装置,研究了不同条件下正、负直流电晕放电的起晕电压、平均电流等特性,获得了正、负直流电晕放电和正脉冲电晕放电的时间积分图像及正脉冲电晕放电的时间分辨图像。还分析了介质尺寸、形状、填充密度以及介电常数对正脉冲电晕放电特性的影响。所得结果表明,填充介质导致正、负直流电晕起晕电压升高。正电晕放电更易于激发填充介质的表面放电,且尺寸小的介质颗粒更容易形成环绕颗粒表面的放电。在正脉冲电晕放电中,填充介质密度、介电常数越高,起晕电压越低;球状介质比圆柱形介质更容易形成表面放电。     

川藏铁路雅安至林芝段工程地质环境及主要工程地质问题（特约稿）

为全面掌握川藏铁路雅安至林芝段沿线区域工程地质环境,查清主要工程地质问题,为建设施工和通车运营提供科学依据,通过归纳总结各阶段勘察设计、科研专题研究成果,详细阐述了川藏铁路雅安至林芝段工程地质环境,系统分析了主要工程地质问题,提出铁路减灾选线原则,主要工程地质问题的工程对策建议,施工和运营阶段需要重点关注的重大工程地质问题及研究重点。研究结论表明：1）川藏铁路雅安至林芝段具有显著的地形高差、强烈的板块活动、频发的山地灾害、敏感的生态环境、恶劣的气侯条件、薄弱的基础设施等六大工程环境特征,也是面临的六大挑战。具有工程建设环境极其恶劣、铁路长大坡度前所未有、超长深埋隧道最为集中、山地灾害防范任务艰巨、生态环境保护责任重大五大工程建设难题。具有高原高山峡谷区地理数据快速准确获取难、地质灾害早期识别评估难、超级工程与物流保障难、生态环境风险大、重大工程建设及防控风险大等“三难两大”风险。2）研究区域属大型滑坡、冰川泥石流、冰湖溃决等山地灾害的集中区和易发区,并且各类灾害在复杂的环境条件下易形成链生性灾害;研究区域内的活动断裂与高烈度地震、高地应力、高地温、高压涌突水等多场耦合下的深埋隧道重大不良地质发育,影响和制约铁路工程选线及工程建设;3）采用“空天地”综合勘察手段,查明研究区的主要工程地质问题,通过采用隧道穿越方式绕避大型复杂的浅表地质灾害、采用减少埋深、缩短长度、傍山靠河、走行于相对低温廊道、避开长大水平径流区等针对性工程措施,可有效应对浅表层及隧道不良地质问题。4）本研究成果可指导川藏铁路建设施工运营,也可为滇藏、中尼等铁路的勘察设计及建设施工提供参考。