Influence of Solar Wind on the Global Electric Circuit,and Inferred Effects on Cloud Microphysics,Temperature, and Dynamics in the Troposphere

There are at least three independent ways in which the solar wind modulates the flow of current density (Jz) in the global electric circuit. These are (A) changes in the galactic cosmic ray energy spectrum, (B) changes in the precipitation of relativistic electrons from the magnetosphere, and (C) changes in the ionospheric potential distribution in the polar caps due to magnetosphere-ionosphere coupling. The current density J _z flows between the ionosphere and the surface, and as it passes through conductivity gradients it generates space charge concentrations dependent on J _z and the conductivity gradient. The gradients are large at the surfaces of clouds and space charge concentrations of order 1000 to 10,000 elementary charges per cm³ can be generated at cloud tops. The charge transfers to droplets, many of which are evaporating at the cloud-clear air interface. The charge remains on the residual evaporation nuclei with a lifetime against leakage of order 1000 sec, and for a longer period the nuclei also retain coatings of sulfate and organic compounds adsorbed by the droplet while in the cloud.The charged evaporation nuclei become well mixed with more droplets in many types of clouds with penetrative mixing. The processes of entrainment and evaporation are also efficient for these clouds. The collection of such nuclei by nearby droplets is greatly increased by the electrical attraction between the charge on the particle and the image charge that it creates on the droplet. This process is called electroscavenging. Because the charge on the evaporation nuclei is derived from the original space charge, it depends on J _z, giving a rate of electroscavenging responsive to the solar wind inputs.There may be a number of ways in which the electroscavenging has consequences for weather and climate. One possibility is enhanced production of ice. The charged evaporation nuclei have been found to be good ice forming nuclei because of their coatings, and so in supercooled clouds droplet freezing can occur by contact ice nucleation, as the evaporation nuclei are electroscavenged. Although quantitative models for the all the cloud microphysical processes that may be involved have not yet been produced, we show that for many clouds, especially those with broad droplet size distributions, relatively high droplet concentrations, and cloud top temperatures just below freezing, this process is likely to dominate over other primary ice nucleation processes. In these cases there are likely to be effects on cloud albedo and rates of sedimentation of ice, and these will depend on J _z.For an increase in ice production in thin clouds such as altocumulus or stratocumulus the main effect is a decrease in albedo to incoming solar radiation, and in opacity to outgoing longwave radiation. At low latitudes the surface and troposphere heat, and at high latitudes in winter they cool. The change in meridional temperature gradient affects the rate of cyclogenesis, and the amplitude of planetary waves. For storm clouds, as in winter cyclones, the effect of increased ice formation is mainly to increase the rate of glaciation of lower level clouds by the seeder-feeder process. The increase in precipitation efficiency increases the rate of transfer of latent heat between the air mass and the surface. In most cyclones this is likely to result in intensification, producing changes in the vorticity area index as observed. Cyclone intensification also increases the amplitude of planetary waves, and shifts storm tracks, as observed.In this paper we first describe the production of space charge and the way in which it may influence the rate of ice nucleation. Then we review theory and observations of the solar wind modulation of J _z, and the correlated changes in atmospheric temperature and dynamics in the troposphere. The correlations are present for each input, (A, B, and C), and the detailed patterns of responses provide support for the inferred electrical effects on the physics of clouds, affecting precipitation, temperature and dynamics.     

Solar Wind Control of the Magnetospheric and Auroral Dynamics

A dependence of the polar cap magnetic flux on the interplanetary magnetic field and on the solar wind dynamic pressure is studied. The model calculations of the polar cap and auroral oval magnetic fluxes at the ionospheric level are presented. The obtained functions are based on the paraboloid magnetospheric model calculations. The scaling law for the polar cap diameter changing for different subsolar distances is demonstrated. Quiet conditions are used to compare theoretical results with the UV images of the Earth’s polar region obtained onboard the Polar and IMAGE spacecrafts. The model calculations enable finding not only the average polar cap magnetic flux but also the extreme values of the polar cap and auroral oval magnetic fluxes. These values can be attained in the course of the severe magnetic storm. Spectacular aurora often can be seen at midlatitude during severe magnetic storm. In particularly, the Bastille Day storm of July 15–16, 2000, was a severe magnetic storm when auroral displays were reported at midlatitudes. Enhancement of global magnetospheric current systems (ring current and tail current) and corresponding reconstruction of the magnetospheric structure is a reason for the equatorward displacement of the auroral zone. But at the start of the studied event the contracted polar cap and auroral oval were observed. In this case, the sudden solar wind pressure pulse was associated with a simultaneous northward IMF turning. Such IMF and solar wind pressure behavior is a cause of the observed aurora dynamics.     

Wind in the Solar Corona: Dynamics and Composition

The dynamics of the solar corona as observed during solar minimum with the Ultraviolet Coronagraph Spectrometer, UVCS, on SOHO is discussed. The large quiescent coronal streamers existing during this phase of the solar cycle are very likely composed by sub-streamers, formed by closed loops and separated by open field lines that are channelling a slow plasma that flows close to the heliospheric current sheet. The polar coronal holes, with magnetic topology significantly varying from their core to their edges, emit fast wind in their central region and slow wind close to the streamer boundary. The transition from fast to slow wind then appears to be gradual in the corona, in contrast with the sharp transition between the two wind regimes observed in the heliosphere. It is suggested that speed, abundance and kinetic energy of the wind are modulated by the topology of the coronal magnetic field. Energy deposition occurs both in the slow and fast wind but its effect on the kinetic temperature and expansion rate is different for the slow and fast wind.     

基于一维卷积神经网络和SoftMax分类器的风电机组行星齿轮箱故障检测

将卷积神经网络引入风机故障检测领域,设计了一种一维卷积神经网络的结构,并和SoftMax分类器相结合构造了一种双层智能诊断架构。一维卷积神经网络用于行星齿轮箱数据的特征提取,SoftMax分类器对提取的特征进行分类。与传统智能算法相比,该方法具有训练样本少,可直接使用原始数据训练网络;计算效率高,可以适应实时诊断的需要。试验结果证明,该方法可以有效地诊断出不同工况下的行星齿轮箱中的齿轮故障。     

波音737NG飞机后机身涡流发生器断裂分析

介绍了X航波音737NG飞机后机身涡流发生器频繁发生的断裂以及在役丢失状况,并从涡流发生器的运行环境和安装参数等方面着手,对其断裂的原因和预防措施进行探讨。     

Prognostic Health Management of Aircraft Power Generators

In this paper, prognostic tools are developed to detect the onset of electrical failures in an aircraft power generator, and to predict the generator's remaining useful life (RUL). Focus is on the rotor circuit since failure mode, effects, and criticality analysis (FMECA) studies indicate that it is a high priority candidate for condition monitoring. A signature feature is developed and tested by seeded fault experiments to verify that the initial stages of rotor faults are observable under diverse generator load conditions. A tracking filter is used to assess the damage state and predict generator RUL. This information helps to avoid unexpected failures while reducing the overall life-cycle cost of the system.     

低速风洞动态试验的高速并联机构设计及动力学分析

为模拟飞行器多自由度(DOF)风洞试验,设计并制造了一种用于低速风洞试验的高速并联六自由度机构,综合分析需求和机构的约束条件,确定机构的结构参数,并分析和总结了该机构的特点。使用ANSYS软件计算系统的固有频率,得到系统极限位置的振动响应。利用ADAMS软件对机构进行柔性动力学仿真,模拟机构在高速运动时紧急制动的动力特征,比较分析刚性和柔性制动的冲击载荷,总结出机构高速制动的特点,所分析结果在机构的设计和实际应用中具有重要的意义。实际运行表明:并联机构可实现单自由度和多自由度耦合运动,具有大工作空间(振幅可达30°/500mm)、高运动精度(达0.05°/0.5mm)和高速(达5m/s)等特点,并具有较高的运动性能,满足风洞试验要求。     

信息网络管理问题研究

从信息网络安全、网络知识产权和网络商业秘密保护几个方面阐述了信息网络管理上存在的若干问题，并提出自己的见解。     

超燃进气道分离流动的凸起物控制机理研究

双模态超燃冲压发动机由于压力扰动可能发生不起动现象,造成推力严重下降,对飞行稳定性与飞行安全具有很强的破坏性。不起动初始阶段主要受到激波与边界层相互作用引起的流动分离影响,采用5阶特征型WE-NO格式与3阶TVD型Runge-Kutta格式的高精度数值方法,求解三维Navier-Stokes方程,研究了利用凸起物作为涡发生器的被动控制方法,及其对高超声速流动分离现象的控制效果。结果表明高精度数值格式能够捕捉到复杂精细的流动分离结构,总结了摩阻、压力等在分离再附位置的变化规律;发现凸起物通过诱导形成局部流向涡进行流动控制,能够改变压力分布,减弱分离强度,影响分离结构。     

Coordinated Frequency and Voltage Control of Synchronous Generators

Three different types of controllers, i.e., the conventional controller, the linear optimal controller (LOC), and the variablestructure controller (VSC) are proposed for the coordinatedfrequency and voltage control of synchronous generators. Theinteraction between the frequency and voltage control loops is takeninto account by incorporating both the speed-governing system andthe excitation system into the mathematical model of thesynchronous generator. Results obtained from computer simulationindicate that the variable structure controller can yield the bestdynamic responses following a step load change.     

旋涡发生器对射流的噪音特性及引射能力的影响

本文在亚音速喷流情况下,就旋涡发生器对其噪声特性及引射能力的影响进行了实验研究。结果发现,在收缩喷管出口处安装的旋涡发生器使出口Ma=0.5的射流噪音大大降低,而出口掺混区长度大大缩短,证明其引射能力大大增强,其中,加装四个角向对称的旋涡发生器的效果最佳。     

Optimal Design of Induction Generators for Space Applications

A high frequency electromechanical energy conversion option for space power applications is introduced. An induction generator (IG) operating at high frequencies is an excellent option for obtaining high power and energy densities. Various design aspects affect the operating characteristics of the machine. The effects and consequences of specific trade-offs in the design process are explored. The methodology is helpful in evaluating specific choices for materials as well as machine configurations. Use of power semiconductor devices and other power electronic devices is avoided to provide immunity from radiation and electromagnetic interference.     

Analysis of Polyphase Commutator Generators for Wind-Power Applications

This paper describes the mathematical modeling of the ac polyphase hase commutator generator by means of Park's equations. For clarity, a two-phase, balanced-operation machine is analyzed. Equations ions of performance are developed in terms of familiar parameters. The machine is shown to have attractive characteristics for variablespeed peed constant-frequency power generation, with possible application to wind-power systems.     

Design of SIMO Excitation Controllers for Synchronous Generators

Stabilization of synchronous generator oscillations is investigatedby using a single-input multiple-output (SIMO) excitation controller.The feedback signals which are most effective for the damping ofelectromechanical oscillations are selected based on the participationfactors of various signals. In order to improve the dampings ofpoorly damped oscillation modes, the eigenvalues associated withthese modes are shifted to certain prespecified locations by adjustingthe parameters of the excitation controller. Time domain simulationresults are also presented to show the validity of the proposedmethod.     

涡流发生器对轴流压气机叶顶流动不稳定性影响的实验研究

为了探究涡流发生器对轴流压气机叶顶流动不稳定性的影响,在一台低速轴流压气机转子上开展了实验研究。将梯形和半球形两种涡流发生器分别安装在转子叶顶上游机匣上,基于不同的安装角度共制定了五种控制方案。分析了气动性能的变化,并采用频谱分析和统计分析方法考察了壁面脉动压力特性的变化。实验结果表明：采用梯形涡流发生器后,除安装角为90°的方案外,其它方案在各工况下扩压能力均略有下降,失速时的流量也明显减小。在流场存在旋转不稳定性或失速的工况,-45°方案时涡流发生器增加了来流的正预旋,增加了气流动量,同时产生的诱导涡会径向迁移,进而抑制了叶顶区域的旋转不稳定性或旋转失速的强度。     

基于边际效用理论的飞机维修模式的探讨

为提高飞机维修的经济性,采用经济学领域的边际效用理论对飞机维修效用、维修边际效用和维修总效用进行了定义,为量化飞机维修效用,建立了数学模型,对维修效用进行定量计算.所建立的边际维修理论对于维修经济性的提高和定量计算有一定的指导作用.     

凹型面埋入式涡流发生器控制分离流

本文介绍了一种新型的凹型面埋入式涡流发生器的工作机理。并介绍在一个小宽高比二元单边凹壁亚声扩压壁前段出现气流分离,角落区域有倒流的情况下,采用适当几何参数的该型式涡流发生器大大减小分离区的范围,从而提高了扩压器静压恢复系数和减小总压损失系数的试验结果。     

任意波发生器的校准思想及技术述评

主要介绍了JJF1152-2006《任意波发生器校准规范》中所采用的校准原则、思想和技术.针对任意波发生器实际校准和应用中需要面对的一系列问题,讨论了任意波发生器的技术内涵和实质;提出了其校准的主导思想:仪器设备的校准、波形生成能力的校准、波形生成质量的校准;确定了校准的主要内容:仪器设备极限参数的校准和失真特性的校准;介绍了任意波发生器校准所采取的技术措施:虚拟仪器模式下的模型化测量方法;讨论了校准仪器设备选取原则:通用性原则、溯源性原则和最简捷原则和高精度原则.针对主要校准项目参数,讨论了几种典型校准方法的优缺点.     

网络化空中交通管理系统

随着信息、通信和卫星技术在航空领域的广泛应用,民航空中交通管理方式正在发生深刻的变革。未来空中交通管理系统将以高可靠性、可用性、完好性、实时／准实时的网络化通信、导航、监视为基础,为用户提供全球范围、全天时、全天候的一体化、无缝互联的实时协同空中交通服务。