Fe/O Ratios in Interplanetary Shock Accelerated Particles

It is widely accepted that diffusive shock acceleration is an important process in the heliosphere, in particular in producing the energetic particles associated with interplanetary shocks driven by coronal mass ejections. In its simplest formulation shock acceleration is expected to accelerate ions with higher mass to charge ratios less efficiently than those with lower mass to charge. Thus it is anticipated that the Fe/O ratio in shock-accelerated ion populations will decrease with increasing energy above some energy. We examine the circumstances of five interplanetary shocks that have been reported to have associated populations in which Fe/O increases with increasing energy. In each event, the situation is complex, with particle contributions from other sources in addition to the shock. Furthermore, we show that the Fe/O ratio in shock-accelerated ions can decrease even when the shock is traveling through an Fe-rich ambient ion population. Thus, although shock acceleration of an Fe-rich suprathermal population has been proposed to explain large Fe-rich solar particle events, we find no support for this proposal in these observations.     

(高)超声速流动试验技术及研究进展

近年来,与高速飞行器相关的(高)超声速流动受到了极大的关注。这类流动所具有的非定常性、强梯度和可压缩性对试验方法和风洞设计技术提出了挑战。超声速纳米示踪平面激光散射(NPLS)技术是由作者所在团队研发的非接触光学测试技术。它能够以较高的空间分辨率来揭示超声速三维流场的一个瞬态剖面的时间解析的流动结构。介绍了NPLS技术以及基于NPLS开发的密度场测量、雷诺应力测量和气动光学波前测量等方法,并回顾了这些技术在超声速边界层、超声速混合层、超声速压缩拐角、激波/边界层相互作用和光学头罩绕流等流动中的应用,清晰地再现了边界层、混合层、激波等典型流场结构及其时空演化特性。另外,为了模拟和研究高空大气条件下边界层自然转捩和超声速混合层的转捩特性,介绍了高超声速静风洞、超-超混合层风洞的设计技术以及层流化喷管的设计方法。     

爆炸冲击载荷下典型机身结构动响应及破坏

确定满足适航要求的最小风险炸弹位置,必须研究爆炸冲击载荷下机身结构动响应及破坏模式。以某型飞机典型机身结构为研究对象,采用LS-DYNA商用软件,建立了爆炸冲击载荷下机身典型结构动响应数值模型。采用控制变量法分析了爆炸物当量、爆炸冲击距离以及爆炸冲击位置对典型机身结构动响应及破坏模式的影响,同时研究了损伤后典型机身结构的剩余强度。研究结果表明,造成机身结构有效破坏的爆炸物临界当量与爆炸冲击距离密切相关;爆炸冲击距离对典型机身结构损伤及剩余强度影响不明显;典型机身结构筋条位置对剩余强度影响较大。在此基础上,提出了表征剩余强度的无量纲系数,并建立了剩余强度无量纲系数与爆炸物当量及爆炸冲击距离之间的函数关系。     

大气准两年振荡对赤道行星波上传的影响

本文讨论了热带大气行星波在QBO风场中向上传播的规律,并运用数值模拟的方法,得到了开尔文波和混合罗斯贝重力波在QBO不同相位下交替上传的结果。试图用QBO对行星波的调制解释QBO在日地相关性中的作用.      

极区中层惯性重力波的VHF雷达观测

本文采用ＳＯＵＳＹＶＨＦ雷达１９８７年６月在挪威Ａｎｄｏｐｖａ（６９°Ｎ，１０°Ｅ）的观测数据，研究中层惯性重力波的传播特征．几个周期为数小时的准单色波例子，在垂直方向上有确定的相位移动，表明它们是惯性内重力波．通过分析波相关的流体速度东向和北向分量的变化，获得水平传播矢量的大小和方向，它们与中层高度上典型的观测值一致．同时还观察到三个等相面上行的惯性重力波，其速度偏振椭圆是逆时针旋转的．波相关的扰动速度为１５－４０ｍ／ｓ，说明在中层存在强烈的向下的能量传输．估算出它的运动学参量，周期为数小时，垂直相速度在０．ｌ—０．６ｍ／ｓ之间，垂直波长约为６．０ｋｍ．     

极区中层惯性重力波VHF雷达观测的统计特征

本文采用ＳＯＵＳＹＶＨＦ雷达１９８７年６月２２日至６月２９日在挪威Ａｎｄφｙａ（６９°Ｎ，１０°Ｅ）的观测数据，研究中层惯性重力波传播的统计特征．２１个周期为数小时的准单色波例子，在垂直方向上有确定的相位移动，表明它们是惯性内重力波．通过分析波相关水平扰动速度的矢端曲线，获得了水平传播矢量的大小和方向的分布，大多数（７６％）波具有西向传播的波矢分量，似乎与中层顶具有强的西向背景风有关；水平传播速度的大小与中层高度上典型的观测值一致．本文分析结果还表明在极区中不仅存在向上的能量传输，也存在强烈的向下的能量传输．     

GRECO与行波求解低散射目标后向RCS

GRECO(Graphical Electromagnetic Computing)技术是目前分析高频区复杂目标雷达散射截面(RCS)最有效方法之一.对低散射截面目标而言,行波效应往往贡献显著,在行波效应较强的某些区域,行波值甚至超过面元与棱边贡献,本文通过GRECO与行波混合法求解低散射目标后向RCS.利用低散射支架为实例,给出与实验结果符合良好的RCS曲线,具有工程实用价值.      

RCS分析中多次反射的计算及程序实现技术

介绍目标RCS分析计算中多次散射的计算方法,计算多次散射时主要考虑面元-面元之间的相互作用,计算过程采用几何光学法(GO)、物理光学法(PO),在总后向RCS计算中还运用了等效电磁流法.同时,文中讨论计算多次散射的程序实现技术.最后,给出计算例子,考虑多次散射时总的后向RCS计算结果与前人发表的实验结果相吻合.      

Coronal fast wave trains of the decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare

The 22 min long decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare simultaneously by the Brazilian Solar Spectroscope (BSS) and the Ond?ejov radiospectrograph in frequency range 1200–4500 MHz has been analyzed. We have found that the characteristic periods of about 60 s belong to the long-period spectral component of the fast wave trains with a tadpole pattern in their wavelet power spectra. We have detected these trains in the whole frequency range 1200–4500 MHz. The behavior of individual wave trains at lower frequencies is different from that at higher frequencies. These individual wave trains have some common as well as different properties. In this paper, we focus on two examples of wave trains in a loop segment and the main statistical parameters in their wavelet power and global spectra are studied and discussed.