Influence of wave normal angle on gyroresonance between chorus waves and outer radiation belt electrons

In this paper,using a Gaussian distribution of wave normal angle X=tan,and considering contributions of harmonic resonances n up to±5,we analyze the effect of normal angle on diffusion coefficients induced by gyroresonance between chorus waves and electrons with energies 0.1 and 1.0 MeV on the dayside and nightside at L=4.5.When pitch angle e>10°,for 0.1and 1.0 MeV electrons on the dayside and nightside,diffusion coefficients of five orders(2,1,0,1,2)decrease with increasing normal angle peak,leading to the total diffusion coefficients decreasing with increasing peak.When e<10°,for 1.0MeV electrons on the dayside and 0.1 MeV electrons on the dayside and nightside,the positive order diffusion coefficients are generally smaller than the same negative order ones;in the meanwhile,diffusion coefficients of orders(2,1,2)are very small,the dominant order n=1 diffusion coefficients change very little,hence the total diffusion coefficients almost remain unchanged.However,for 1.0 MeV electrons on the nightside,diffusion coefficients of orders(2,1,2)which are larger than those of the order(1)resonance increase with increasing peak,hence the total diffusion coefficients increase with increasing peak.The current results show that the wave normal angle plays an important role in the quantitative analysis of gyroresonance between chorus waves and electrons in the outer radiation belt.     

降雨诱发黄土边坡失稳室内试验研究

为研究降雨诱发滑坡失稳破坏机理和演化特征,开展了人工降雨条件下黄土滑坡室内研究,通过对土体的体积含水率、基质吸力及坡体变形破坏监测,分析降雨入渗对黄土边坡稳定性的影响.结果表明:在一定的降雨强度范围内,降雨强度越大,降雨入渗速度越快,越易发生滑坡;边坡坡度越缓,坡面降雨入渗速度越快;湿润锋移动在坡脚和坡顶较坡面更快,对滑坡的发生发展有较大影响;试验滑坡为多级后退式破坏模式.     

Mechanism analysis on pillar instability induced by micro-disturbance under critical condition

A simplified mechanical model of ultra-high pillar was established and its potential energy expression was derived under axial load on the basis of energy theory. Under critical conditions according to the nonlinear theory, the critical behaviors and the forming mechanism of pillar instability were discussed by external disturbance , such as stresses waves by blasting , axial force eccentricity ratherish and imperfections in pillar. The results show that the micro-disturbances attenuate with time and they are independence each other when pillar is in the stability state. Their effects on the stability of system are inessential. The correlation degree of disturbances increases sharply and various micro-disturbances are relative and nested reciprocally when the system is in critical state and they also cooperate with each other, which induces system to reach a new state.     

Observations and parametric study on the role of plasma density on extremely low-frequency chorus wave generation

Extremely low-frequency(ELF) chorus waves with frequencies below 0.1 fcecan cause the scattering losses of relativistic electrons. Previous studies have suggested that ELF chorus waves are excited by anisotropic electrons with energies up to a few hundred ke V. Here, we report an interesting event observed using the Van Allen Probes on November 1, 2012, where distinct ELF chorus waves occurred exactly corresponding to the enhancement of the plasma density. Using the correlated data of particles ...     

吉瓦级紧凑型L波段同轴返波振荡器的粒子模拟研究

设计了吉瓦级紧凑型L波段同轴相对论返波振荡器,通过粒子模拟研究了器件内束-波作用的物理过程．模拟结果表明,在电子束能量700keV,电子束流10kA,导引磁场为0.9T时,返波振荡器可以在频率1.60GHz处获得较大的微波输出,饱和后输出微波的平均功率达2.2GW,效率约为30％,器件电磁结构尺寸仅为100mm×520mm．     

燃烧诱发热声不稳定控制的研究进展

针对贫燃预混低NOx燃气轮机的燃烧诱发热声不稳定问题,说明了燃烧热声不稳定的起源、特点和危害,详细阐述了当前燃烧热声不稳定控制研究的现状,分析了热声不稳定的被动控制和主动控制的概念、应用和各自特点。被动控制和主动控制的核心思想是一致的,通过重新设计或外加干扰解耦火焰热释放脉动与声场的相互作用。     

bExperimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

When the sliding mass contains impervious bed, rainfall can infiltrate into mountain via crevices and form higher artesian aquifer at impervious bed inferior. This will decrease slip resistance and increase sliding forces of the sliding mass, thus lowering the safety factor, and inducing landslide disasters. In this paper, a landslide experimental apparatus is designed for experimental studies on the mechanism of this type of landslides. Meanwhile, the non-dimensional parameters in the model experiment are taken into account using dimensional analysis. The experimental results show that (1) the ratio of the cleft water pressure to the overlying pressure is a crucial parameter affecting the stability of the slope; (2) when the shut-in pressure reaches 80% of the normal component of the pressure on the slip surface made up of rock and soil, landslide will occur: (3) the whole slope will start to slide when the shut-in pressure is equal to the normal component of the pressure formed by the overlying rock and soil on the upper 30% area. In this article, a discrete element method simulation is used to investigate the influence of cleft water pressure and shearing strength on the landslide stability. It can be concluded that the critical value of C_cr, ρ_cr, which determines the slide mass stability, increases with the increase of the water pressure; if the water pressure reaches a high level, the stability of the slide mass depends mainly on C, while the influence of ? becomes smaller than C.     

Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

1 Introduction The in situ observations and analysis on the landslide events indicate that water is one of the key factors which induce landslide of the mountain mass[1―8]. The mechanism offissure water inducing landslide can be generalized into three aspects: (1) the softening influence of water weakens the strength of materials on the slip surface[9―11]; (2) the cleft water pressure towards the slide slope free face increases sliding force[12―15]; (3) water pressure on the slip surface lo…     

毫米波降雨去极化分辨率的辨识建模

以双输入、双输出系统辨识的方法,得到了以降雨同极化衰减Ｃｈ和Ｃｙ为输入,以降雨去极化分辨率Ｘｈ和Ｘｖ为输出的参数矩阵模型,提出了一种简便可行、精度较高的求降雨去极化分辨率的方法,结果表明该方法的计算精度能满足要求,对于毫米波的去极化计算很有意义。     

管道联接件参数识别的波动方法

基于波动理论,提出了一种识别管道联接件物理参数的新方法.以直管在平面内的弯曲振动为例,将弯曲波分解为左、右行波和衰减波,建立起管道单元上各测量点功率谱与波谱的关系,并由联接件处位移连续及力平衡条件,将联接件刚度及阻尼表示成波谱的函数.由联接件物理参数的辨识转化为与联接件相连管道单元上波谱的辨识.最后通过数值算例验证了波动方法在管道联接件物理参数辨识中的可行性.结果表明,波动方法在参数辨识中具有良好的识别精度和数值稳定性,是一种极有潜力的参数辨识方法.     

用旋转矢量法研究驻波

用解析法研究驻波比较抽象，利用旋转矢量法直观、形象地研究了驻波的特点。     

含旋转振子的周期基础对地震弯曲波的隔震作用

提出一种含旋转振子的周期性基础（PF）板,用于高层建筑对地震弯曲波的隔震。早期对PF隔震的研究主要针对平面波,但地震波对于周期性基础板结构更易激发弯曲波。突破以往研究仅针对平面波的局限性,对弯曲波输入的频散关系进行探究;通过有限元法,利用可考虑板厚影响的SHELL单元计算PF板的弯曲波衰减域,系统研究材料参数和几何参数对弯曲波衰减域的影响;通过对三维有限元模型进行弯曲波和地震波入射的数值仿真试验,验证PF隔震的有效性。结果表明：弯曲波衰减域对连杆的宽度和弹性模量变化很敏感;在弯曲波输入下,PF的衰减域在10 Hz以下,与混凝土基础板相比,PF对弯曲波的隔震效率大于60%,能够作为高层建筑的隔震基础。     

异向媒质恢复倏逝波作用的研究

为了验证异向媒质（LHM）对倏逝波的恢复作用，提出了一种借助矩形波导的新型仿真模型.在由相位跟踪测量方法得到LHM折射率近似为1的工作频率下，该仿真模型研究了倏逝波通过人工LHM的传输特性，并用有限计算域内的三维时域有限差分FDTD技术对人工异向媒质进行了仿真，获得了倏逝波电场在空波导中的幅度分布.同时讨论了异向媒质电磁参数与理想完美透镜条件的偏差对异向介质对倏逝波恢复作用的影响.仿真结果表明，异向媒质对倏逝波的幅度具有部分恢复作用.该仿真模型可以在有限计算域内单独对倏逝波的性质进行研究，可以应用于验证异向介质对倏逝波作用的实验.     

TCSC改善波浪发电系统的性能分析

比较各种波能转换装置优缺点,并对振荡水柱式发电装置并网运行进行建模.当波浪发电系统并网时,采用TCSC对系统进行无功控制并提高电压稳定性.在正常运行和线路发生故障2种情况下,分别分析TCSC对波浪发电系统的影响.研究结果表明,TCSC所表现的补偿线路阻抗的能力在稳定电压、抑制系统振荡等方面有较好的作用;采用TCSC后的系统静态输送功率极限和暂态稳定性都得到了较大提高.     

超声降解苯胺溶液实验研究

采用超声波辐射降解苯胺溶液对超声波辐射时间、溶液温度、pH值、初始浓度、外加H2O2等因素对降解效果的影响进行了探讨．实验结果表明：该法能有效去除苯胺,去除率随辐射时间的延长而增加;低浓度、碱性有利于苯胺的降解;反应温度控制在30℃以下对超声降解有利;外加H2O2可明显提高苯胺的去除率．     

超声降解苯胺溶液实验研究

采用超声波辐射降解苯胺溶液对超声波辐射时间、溶液温度、pH值、初始浓度、外加H2O2等因素对降解效果的影响进行了探讨.实验结果表明:该法能有效去除苯胺,去除率随辐射时间的延长而增加;低浓度、碱性有利于苯胺的降解;反应温度控制在30℃以下对超声降解有利;外加H2O2可明显提高苯胺的去除率.     

利用超声波辐射提高废水可生化性试验研究

本文介绍了超声波照射提高废水可生化性的基理,研究了超声波照射时间和超声波照射功率对废水可生化性的影响.     

Cloud and precipitation interference by strong low-frequency sound wave

Acoustic interference of atmosphere has been an attractive research area because of its potential effect on environment, water resources, ecology, agriculture, and other areas. However, it is also a controversial topic because of the difficulty of quantitative assessment and high operating costs. In this study, a novel acoustic interference technology is proposed that uses strong lowfrequency sound waves. There is no chemical pollution or dependence on airborne vehicles, and it can be remotely controlled at low cost. A complete equipment system for acoustic atmospheric interference technology is established, based on which a series of experimental studies on cloud and precipitation response under acoustic action are performed, mainly including the radar echo intensity, cloud microphysical characteristics and the spatial distribution of ground rainfall intensity. The trigger and periodic effect of the acoustic waves on the cloud are proposed to be the key responses of acoustic atmospheric interference. This study is important to further research on atmosphere interference technology based on low frequency strong sound waves.